1.- and I'm going to emphasize this a lot.

PAGING

(or at least some concept in the vein of "show only a finite amount of information at a time")

Lemmy does it well, but Mastodon sorely requires it for example. Anything that induces the pattern of autorefreshing, auto-filling, constantly changing timelines only empahsizes the addictions that antisocial media is working with already.

2.- More and better reactions than simply "upvote" and "downvote".

A upvote or a downvote can mean things in different categories, from "I don't like this" to "this is uninformative" to "this is misinformative!" to "enough Musk spam!". Condensing and factoring such results into how threads are found and sorted artificiates any or all of popularity, consensus and usefulness. So, being able to "react" (add a singular tag to a message without the need for a reply) to a message with more options than "upvote" and "downvote" would be useful. I'd count at least three axis (axeses? switchaxes?) that are useful to gauge: "agree - disagree", "informational - misinformational" and "verified - debunked".

3.- Global, or at least shareable and moveable, user identity. Won't comment on this more because others already cover it enough.

4.- Fucking decouple instance identity from DNS. DNS is the layer that big corpo will rein in next, depending on it to validate who an instance is is playing an eventually loser game.