Wall of text about things I learned while trying to leave the US incoming:

Passports to Spain/Portugal/Netherlands/Malta/Greece/Cyprus are buyable but incredibly expensive, you basically have to spend a few hundred thousand to a million or so Euros in property investments in the country. Obviously most people don't have the means to just buy expensive overseas property/business.

Italy is just a popular second passport destinstion because it's one of the most likely for Americans to qualify for and it's relatively easy compared to the rest of Europe, since anyone descended from an Italian citizen (i.e. anyone anyone who resided in Italy in the 1860s or was a citizen afterwords) is also a citizen, with no generational limit. The chain is technically broken by mothers, but you can sue for discrimination and win to get it anyways (this is pretty common).

Something similar also applies for Hungary, except past your grandparents or so you have to actually at least be conversational in Hungarian. But the thing with Hungary is that a Hungarian citizen counts as anyone who has ever been a citizen of a Hungarian state or lived in Hungarian-controlled territory throughout the entire country's history, even if it was 1000 years ago. So if you can reasonably establish that you're descended from anyone who has ever been "Hungarian" and you can speak Hungarian reasonably well, you can get a passport.

I think Lithuania also has similar rules to Hungary but I'm not sure.

Poland is any Polish citizen born since 1920.

Germany is extremely finnicky and can even vary by region, but in general any German citizen until 1904 lost their citizenship after 10 years out of the country so for the most part descendants of Germans who left the country 1914 or afterwards have a decent case for citizenship by descent. But I've seen people successfully gain citizenship from ancestors born in the 1890s. It all really depends on the luck of the draw for your embassy agents and the amount of good documents you can muster up. The good thing about Germany is their bureaucracy is extremely quick and I've gotten responses in less than a day of sending questions and requests. Technically they don't allow dual citizenship, but the law is changing soon and they have been making exceptions (something not very common in immigration, mind you) for that for a while now, for US citizens at least.

Slovakia is generally pretty lenient, if you have a grandfather or great-grandfather from the Slovak portion of Czechoslovak territory since like 1900 (maybe even before) then you might qualify for citizenship by descent. This is actually what I'm going through right now (since my non-biological great grandparent came here from Slovakia), and while it's very time consuming and relatively expensive (I'll probably end up spending more than a few hundred dollars, probably a few thousand, over the next year or two before it's over) it is possible to do without hiring an immigration lawyer (which cost thousands to tens of thousands of dollars). Be warned that Slovak bureaucracy is well-known for... not being so quick.

There's also the "Slovak Living Abroad" certificate to which you can get residence without actually having Slovak citizenship by descent, it's provided if you can prove considerable cultural ties to Slovakia and that you've helped contribute to Slovak culture abroad (you have to have Slovaks and others holding the SLA vouch for you too).

Czechia is less forgiving than Slovakia in this regard but it's still likely you qualify if you're a Czech citizen.

For Ireland and UK, it's if you have grandparents from Ireland/UK or parents who are Irish/British citizens.

For Switzerland I think only Switzerland-born citizens pass it down.

For Netherlands, grandparents born in the country pass it down.

Nordic countries are very strict on citizenship by descent and only allow you to claim citizenship before your 21st birthday if you have a citizen parent from the country.

Dual citizenship is completely illegal under any and all circumstances in Austria, but those with Austrian parents qualify for citizenship (you must renounce all other citizenships).

For Ukraine, dual citizenship is completely illegal (but the enforcement of that is complicated), those with immediatle family (including siblings) who were born in or lived in Ukraine between 1917 and 1991 qualify.

Spain and Portugal allow those with grandparents who are citizens to pass down citizenship. They used to accept anyone descended from Sephardic Jews who left the country in the 1500s, but I think they met a quota or something and then stopped accepting those applications recently.

You can technically gain citizenship to France if you're recommended by a higher-up after serving a few years in the French Foreign Legion, but you don't want to do this. I highly advise staying as far away as possible from the FFL, and on the off-chance that you even get past training, the odds aren't in your favor for applying to citizenship even after years of service.

Having residence or citizenship in an EU country makes you a resident or citizen of the EU, and allows free travel and work throughout the Schengen zone, and you get almost all of the benefits of being a citizen of all EU countries you are in.

Other than buying citizenship or going through the process of citizenship by descent, the only realistic way to get permanent residence in a European country is by having years of experience in a highly valued field and getting a work visa / blue card (or in Germany's case, just find an employer willing to hire you and the government will allow you to stay) and work in the country continuously for a few years (usually 5 years). You may have to contact an embassy or look up the jobs the government of the particular country values, but in general they want: engineers, software developers, other STEM, medical professionals, tradesmen. And you'll probably only have a chance of being considered if you have at least around 3 years of experience working in the field.

Another option if you're young and have the proper credits is college, although this is usually pretty expensive – but it can be very cheap in most of Germany, Finland, even LatAm countries like Panama, since they have free tuition for foreigners and very low-cost housing for students. Norway/Denmark used to have free tuition for foreigners, but last year they stopped doing that and now only allow EU citizens to go to have no tuition costs. This is an option for people who did very well in high school or who have already completed a Bachelors (sometimes even an Associate's is enough), but if you didn't then you're out of luck and only qualify after you get a degree.

I have ADHD which was completely untreated all throughout highschool so I did pretty terrible there, I wasn't exactly rich, etc. etc. so my only realistic option at the time I began searching other than acquiring my Bachelor's degree as soon as possible was to try to find some way I could get citizenship by descent. I had no physical genealogical records so I had to do all my searching just by working my magic with internet tools and Google search using the names of the family members I knew. Apparently I'm generically Anglo as fuck and all my ancestors were the first motherfuckers to land on this continent, so the only foreign ancestors I had were English/Welsh/Irish/French/German/Dutch/Swiss/Swedish/Austrian people from 150 to 300 years ago and there wasn't a hint of an ancestor that'd actually qualify me. Well until recently where I found Hungarians who I can trace with birth certificates all the way to the Habsburgs, but I don't want to be the one to have to acquire and pay for all of those records/certificates so that's a last resort...

But I also figured out that the grandparent who raised me and who I've lived with my entire life, who I'm not biologically related to and complicatingly didn't actually adopt me or gain guardianship of me (instead being married to my biological grandparent who gained guardianship of/adopted me) had Hungarian, Slovak, and German parents who moved to the US right after the 20th century began. Obviously the weird legal situation complicates things, but I was able to obtain documents from the Slovak government and all that's really left is to go through the slodge of getting all my documents certified/apostled/translated, getting a shit ton of documents from the US government, basically just slow, tedious, and expensive stuff. But I have the means to do it now and it's just a waiting game now, and I'm confident that it'll end with me gaining citizenship (even if it takes 3 to 5 years). And I plan to still do all of it without a lawyer.

Honestly though it'd be easier if I just gained the work experience I needed (software developer here) or finished my degree and did my Master's in the EU (Computational Linguistics) and applied after that, but at least this way I definitely have permanent residence/citizenship and I'm not subject to change of rules/attitudes and instability during a hypothetical work visa residence.

Honestly though it'd be easier if I just gained the work experience I needed (software developer here) or finished my degree and did my Master's in the EU (Computational Linguistics) and applied after that, but at least this way I definitely have permanent residence/citizenship and I'm not subject to change of rules/attitudes and instability during a hypothetical work visa residence.