First Post/Asking for Advice

Hello everyone! I have been lurking here for awhile and I decided it was about time I actually post here. I was hoping to ask for advice or just know if anyone is in a similar situation as me. I've been a ML for awhile now but my parents are hard-core white supremacists/Trump supporters. To the point where they're more extreme than many you would find online. The only difference is that they were born and raised in Africa and my entire family is black. Things have taken a concerning turn with them supporting the ICE shootings and still supporting Trump despite all the Epstein file stuff. They even took the side of the kid who bullied my brother and called him the n word .I've accepted that they're a lost cause since they've always been like this. I'm more concerned about my brother who lives with them. They've started pushing him down the far right rabbit hole and now he seems like an entirely different person. I understand that he's still a teenager but I'm concerned that this behavior won't stop once he becomes an adult. My parents are pretty toxic in general (don't want to go into too much detail) and they've made him entirely dependent on them. They monitor all his internet usage to make sure he only consumes far right politics. I've tried doing what I can but any time my brother feels like I'm trying to change his mind he shuts down or threatens to tell my parents which is pretty bad since despite me being in college they control all my finances and have access to all my bank accounts and there's not much I can do without them reacting horribly. My brother has ADHD and Autism (which my parents refuse to accept or allow him to get help for) which makes it harder for him. He wants to stay near my parents for college and likely for as long as they stay in the US which will be until they retire. I was just hoping for some advice/comfort since my brother is my best friend and it's sad to see him become hateful and abandon his passions. I'm starting to become scared of the adult he will become. Especially since I'm black it is very hard to find a group online with people that will understand. Sorry for the long first post.