Not by me, at least not 100%
I'm convinced he was immersed in a video game subculture that fetishized violence and happened to use some memes that are also associated with the Groyper movement.
I'm convinced that he was registered to vote as an Independent but didn't bother to vote in the last couple elections, indicating either a) disinterest, b) sense of insignificance, or c) disorganization.
I think there is as much evidence (meaning, thin) that he was a young person developing schizophrenia (right age) and with other mental health issues, as that he was a committed member of any specific political group.
It's mostly speculation at this point.
One thing that I think we can bank on, he was not a left-wing activist or radicalized by left-wing propaganda, as the reich-wing wants us to believe.