My gestalt take on everything we’ve seen so far is that, like you said earlier, he was very troubled, but not delusional/psychopathic. He’s a smart kid but has failed to launch. The fact that he is in a romantic relationship with a biological male furry that is transitioning to female probably means he’s a closeted gay man and feels resentful of the strict religious/conservative culture in Utah. He’s aimless, without purpose, and spends most of his time in online communities that are not explicitly political, but to the extent politics are discussed everyone holds the opinions of the average Bluesky or CR poster and Republicans are considered fascists.
When he hears Charlie Kirk is coming to his university he gets the idea into his head that he has the chance for meaning in his life, to slay a dragon that he perceives as a danger to his lover and who is universally reviled in the online circles he frequents. He sees a chance to “stop the hatred” not understanding the second order effects he is going to unleash on the country and those that he loves.
I haven’t seen any evidence that there was a larger conspiracy or others that plotted with him, or that he was part of Antifa or the DSA, even if he may have agreed with some or many of their positions if he ever thought them through.
I agree with all of this, except the nutbar part. Oswald was a communist who assassinated a Cold Warrior President, not as a Soviet agent, but driven by his ideology and own loser-in-life status. Tyler Robinson seems very similar in his motivations. While we might consider anyone who commits a political assassination of their own plan (that isn’t Carlos the Jackal) to be crazy by definition, neither was incapable of understanding what they were doing like a Jared Loughner or John Hinckley. I think they both had delusions of grandeur that they were serving a larger cause, but not that they were hearing voices telling them they were fighting demons like a paranoid schizophrenic.