We've merged Essem's version of emoji reactions (with the support to see, send, and be notified about them).
https://github.com/glitch-soc/mastodon/pull/2462
This is already being used at wetdry.world and other instances:
https://wetdry.world/@notwikipedia/112193635990196847
If things don't work out, we can revert until it gets better.
Federation of the reactions is still limited, like likes/favourites and replies (like reactions added on a post from another instance, it doesn't push the update to everyone else), but it's better than nothing so far.