... as it doesn't come at the cost of the national language.

What is a 'national' language? Who defines a 'nation'?

Can the Chinese Communist Party define that all Uyghurs, Tibetans, Mongolians whose territories are occupied are now Chinese that must be taught only in Mandarin?

Can Russia rule that Ukrainians in the occupied territories can't be taught in Ukrainian as this would "come at the cost of the national language"?

As one scholar from Turkey writes:

Numerous studies in linguistics, psychology, anthropology, and educational sciences demonstrate that monolingual education deepens linguistic, cognitive, and psychological inequalities among children. It not only places children at an academic disadvantage but also damages their relationship with their cultural identities. This leads to a loss of self-confidence at the individual level and to exclusion and alienation at the societal level. In this way, the education system becomes a mechanism that reproduces inequalities rather than eliminating them ...

Epistemic hierarchies, frequently found in colonial modes of thought, position certain languages as “central” and “universal,” while relegating others to “local” and “secondary” status ... Research, however, shows that children learn more rapidly in their mother tongue, that their conceptual development progresses more healthily, and that their cultural identities are strengthened. Mother-tongue education not only increases academic achievement but also enables children to feel equal and valued in the public sphere.

Lasting social peace is possible not where differences are suppressed, but where they are recognized and institutionally guaranteed. When the education system ceases to function as an instrument of homogenization and standardization and instead becomes a vehicle for pluralism, the principle of equal citizenship will acquire its genuine meaning ...

Emphasis mine.

In america, they forced the native americans to learn and speak english. Now the vast majority of the native americans culture has been completely lost forever. But atleast they can all speak english in unity.... right?

You just listed like eight examples of minority languages being protected in Europe. What is the threshold you’re searching for here to prove that minority language and culture are, at least sometimes, treated differently in Europe? I’m in no way suggesting that these issues are being dealt with perfectly anywhere in the world, or that Europe doesn’t have plenty of examples of minority populations being mistreated, but I think it’s kind of strange to argue that China isn’t engaging in some form of ethnic cleansing. Especially when it comes to Tibet and the Uyghur people. The Chinese government is using policies like this to intentionally suppress the culture and language of minority populations.

Both things can be true; Europe has an imperfect record when it comes to treatment of ethnic minorities, and China is targeting certain ethnic minority populations under the guise of “assimilation”.

There are language schools, but I can’t find any details about full education being available in a minority langauge.

I mean... Belgium literally has three different full-fledged education systems in flemish, french and german; all of them with their own curricula, schools, universities, etc.

Due to their similar language they are mostly bilingual and can relatively easily understand each other.

This is just flat out wrong??? Finnish and swedish are not similar languages and they're not mutually understandable. A finnish speaker cannot understand a swedish speaker. Swedish is a germanic language, Finnish is blood uralic, its not even part of the indo-european family. Perkele, mita vittua?!
Did you just go "oh, they're both in the north, they sound similar to me sooooooooooooooo"

Spanish is the only official language in Spain, only autonomous regions are allowed to have their own official languages per the constitution.

By definition its not the ONLY official language if areas in the country have extra official languages.
The very constitution of the country allows for co-official languages.

And overall it makes sense that these minority-language schools are present only in particular regions. Why would you want to have schools for language X when there's not a consistent minority that speaks language X in that area in the first place? Complete waste of resources.
And naturally you can't have schools for every minority, especially with modern-day migration, but its not economically feasible to have a school where only 3 kids can attend.
If would've just said that not every minority in Europe gets its school, I would've agreed. That much is clear. But that is a very different point from the one initially made.
The dominant model in Europe is certainly not one similar to the one China is pursuing, in fact I'd argue that there's few EU member states that come close to that. And the ones that spring to mind are the Baltics - Estonia, Lithuania, Latvia - which is an entirely different bag of chips and a whole conversation to be had about how right or wrong they are to pursue something like that in their present geopolitical context.

and Finnish have the same status as Swedish in Finland due to language similarities

Please, stop saying that. The two languages are not similar. That's not the reason for their status. Its because Swedish imperialism. They occupied Finland for centuries. To help you better understand, percentage-wise the similarity between Swedish and Finnish is CLOSE TO 0% (ZERO)

There is a strong push to encourage foreign languages as secondary

Strong push? I don't agree with this framing. It makes it seem like its just beginning, like only now we're moving in that direction. When the reality is that its completely normalized across most if not all EU member states.
Teaching at least one foreign language is a long-term standard of the education system of EU states.

In 2023, 89% of pupils in upper secondary education in the EU were learning English as a foreign language: this share was 96% in general programmes and 80% in vocational programmes.