Honestly, I’ve seen the Fediblock thing on Mastodon, and it’s…pretty terrible. A whole lot of minority groups get targeted disproportionately by that stuff, especially by misinformation about their instances. The answer is really to leave instances if you disagree with moderation policies and the admins won’t listen, and to join instances that are philosophically aligned with you, because unlike in a centralized/capitalist model, this actually works at cultivating a community that you can engage with in a healthy manner. If not, and you go with something like Fediblock/the one big blocklist site, you’re just gonna end up with most instances that serve 2SLGBTQIA+ people getting blocked or having more harmful misinformation spread about them. Hell, if a lot of Lemmy had its way, anything but being capitalist and pro-USA would be banned.
But also, a lot of clients can subscribe to feeds already. ActivityPub is pretty great at cross compatibility with Mastodon and the like. You just subscribe to someone who uses a microblogging platform based on ActivityPub and it’ll show up in your feed.