Brave appears to be selling copyrighted data for AI training and giving third parties the “rights” to that data, while not disclosing its own robot crawler

Yes Firefox supports adblocking and you should switch to this.

Yes you can add extensions to Firefox mobile, I recommend Ublock Origin

Check out https://nextdns.io/ it’s a privacy focused dns resolver but it also lets you include blocklists at the dns level which are the same lists used by stuff like ublock origin. That’ll block adds and trackers at the dns level before they even hit your device. I’ve had it on my android and iOS devices for years. It will even block most stuff in apps as well.

if you’re using android, mull is supposed to be the good privacy fork of firefox

i think it has ad-blocking but i do ad blocking through my router anyway, so idk for sure