mastodon doesn’t “discover” akkoma content and won’t show anything unless you’re following a user from there, which kinda sucks.

I mean – that’s how all of them work. Even Lemmy. Unless your instance administrator joins relays (which have tradeoffs between privacy / effectiveness of blocking) your instance is only ever aware of posts from followed people (and reply threads followed people are involved in)

(also MUCH lighter on server resources, compared to most other twitter-like alternatives)

Mastodon is just unusually heavy, really. Even Misskey & forks are lighter than Masto on the server side (preferring being bloated on the client instead)