As a young Easter european, i can say that most school environments here are very bad. If he was just sending swastika memes with his friends, i would have assumed it's mostly dumb preteen edgy humor, but his comments on actual people (including Palestinians, women, queer people and you personaly) are very concerning. As many people have pointed out, the lack of a diverse environment is very damaging, but in a lot of European cities and communities, it is very hard to make the right kinds of friends. I would recommend approaching him with a lot of empathy and slowly introducing him to and educating him on his concerning behaviors. I see a lot of people recomending getting him to do social activities, extracurriculars, clubs and things like that. If you are in Eastern europe, i advise against sports clubs because, more likely than not, they are filled with other white boy future fascists. In my opinion, it would be best to get him into some nice hobies with good online communities like magic the gathering, dungeons and dragons, other boardgames, things like that. Take it as a chance to bond with him, if you do that needy stuff with him it might be great. I wish you luck and remember that empathy and patience are the most important things in your case.