Souter, most famously (edit: and most recently, not sure about earlier justices in US history) and other SCOTUS justices have dissented

Here’s a summary: https://www.thenation.com/article/archive/how-the-roberts-court-undermined-sensible-gun-control/tnamp/

I barely skimmed it but it touches on the dissenting opinions around the second amendment.

I'll preface this by saying that this linked article isn't exactly about David Souter. He is only mentioned once in the article as someone who supported another's argument in D.C. v. Heller.

Scalia treated the clause ["A well regulated militia"] as merely “prefatory”

I agree with this. Imo, this comes out of how the commas are used: "A well regulated militia" is the first item, "being necessary to the security of a free state" is parenthetical information emphasizing the importance of a well regulated militia, "the right of the people to keep and bear arms" is the second item, "shall not be infringed" is stating the level of protection on both items. Do note that this is only my personal interpretation/opinion.

Stevens pointed out, the term "bear arms" was most commonly used in the 18th century to describe participation in the military.

This is an interesting point to consider, however, it is not, on its own, an argument for the original intended interpretation of the Second Amendment.

"The idea that the founders wanted to protect a right to have a Glock loaded and stored in your nightstand so you could blow away an intruder is just crazy," says Saul Cornell

Aside from this statement being conjecture, if I deviate from the interpretation of the original intent of the Second Amendment, in my opinion, I don't understand why this is a fundamentally negative idea. Why wouldn't one want people to have the means to protect themselves in the event of a scenario that public law enforcement cannot?

Here’s a summary of Souter’s positions:

https://www.ontheissues.org/Court/David_Souter_Gun_Control.htm

Important to note that only the last section in this link is really relevant to the original point being "some legal minds disagree on the entire intent of the 2nd amendment". And that being said, it essentially just reiterates what was said in the first link, albeit without the surrounding opinion piece, and much more to the point (which I do appreciate).

Justice Breyer filed a separate dissenting opinion that, even with an individual-rights view, the DC handgun ban and trigger lock requirement would nevertheless be permissible limitations on the right. The Breyer dissent concludes, "there simply is no untouchable constitutional right to keep loaded handguns in the house in crime-ridden urban areas."

Given the wording of the second amendment (if you interpret "bear" as a person physically arming themselves, and "keep" as the general ownership of firearms) I would agree that this argument is sound.

And here’s a take from a linguist:

https://www.washingtonpost.com/opinions/antonin-scalia-was-wrong-about-the-meaning-of-bear-arms/2018/05/21/9243ac66-5d11-11e8-b2b8-08a538d9dbd6_story.html

The linguist might seem out of place here but I’ve always felt that analysis was pretty damning for SCOTUS’ take during Heller. Been a couple years since I read that article but it really stayed with me.

This was an interesting read. Interpretation of the Second Amendment is certainly a linguistic issue.

From our review of founding-era sources, we conclude that this natural meaning was also the meaning that ‘bear arms’ had in the 18th century. In numerous instances, ‘bear arms’ was unambiguously used to refer to the carrying of weapons outside of an organized militia.”

This is very interesting.

“A man in the pursuit of deer, elk and buffaloes, might carry his rifle every day, for forty years, and, yet, it would never be said of him, that he had borne arms, much less could it be said, that a private citizen bears arms, because he has a dirk or pistol concealed under his clothes, or a spear in a cane.”

This argument is essentially conjecture — they don't argue why it can't be interpreted that way, they just state that it isn't.

“In the 18th century, someone going out to hunt a deer would have thought of themselves as bearing arms? I mean, is that the way they talk?” Clement finally conceded that no, that was not the way they talked: “Well, I will grant you this, that ‘bear arms’ in its unmodified form is most naturally understood to have a military context.” Souter did not need to point out the obvious: “Bear arms” appears in its unmodified form in the Second Amendment.

This appears to be an attempt at linguistic trapping, rather than an argument. Simply because it wasn't colloquial, doesn't necessarily mean that it couldn't be understood in the manner that bear arms doesn't require one to serve in the military.

to be clear, prior to Heller in 2008, there was no assumption that an individual had the right to arms

I can't really comment on this, as it's conjecture. Would you have any sources that show that the consensus prior to Heller was that the Second Amendment didn't grant individuals the right to arms? Regardless, the current supreme court decision is how the constitution is officially interpreted. What that means is that if people were of that opinion prior to Heller, Heller states that those prior opinions were unconstitutional.