Piefed is another instance type that is growing in popularity, and a few instances are now turning on the API. As such, apps are also implementing support.
It would be great if Boost would support it too. Hopefully the extra development overhead isn't too bad.
Some recent discussion: https://piefed.social/post/817564
The page for developers:
https://join.piefed.social/docs/developers/
The API for third-party apps (frontends, bots, etc) is 95% the same as the Lemmy API.
That same link: https://freamon.github.io/piefed-api/
What is even the difference between Piefed and Lemmy?
It has some quality of life features that people seem to like, which Lemmy doesn't have yet. I'm still getting familiar with it myself. I've heard that blocks work better, and that it lets you follow Mastodon/Pixelfed users.
It's made by a different team, and since it's built with Python & Flask, I imagine development is much faster compared to Lemmy (Rust).
There is a comparison of the features here: https://lemmy.ca/post/45413094/16944475