Gotta give my usual spiel here. Allowed users to sue platforms for third party content (revoking section 230) won't go the way you're picturing. Big Tech would benefit from it, because they'd be the only ones who could afford the necessary lawyers. Smaller sites would cease to exist overnight, and there would be no more startups because of the legal liability.
That said I absolutely agree about the app stores. The way they're being pressured to remove Instagram because people MIGHT be using it to plan bad things in a way that the government can't spy on is spine chilling. I'd say this calls for government regulation, expect the government is actively contributing to the problem! In a more sane world, a choice of app stores would be ideal. You can still do this if you're technically inclined, but it's not for the feint of heart, and certain things just don't exist on any alternative app store.