Which collaborative, real-time, preferably self-hostable note app (kinda like Obsidian with the Relay plugin or the Logseq DB version) would you recommend?

Me and a few classmates are hoping to set something like this up for shared class notes.

Obsidian with the Relay plugin seems perfect, but sadly even if you self host it you have to pay to have more than 3 users, and even if you do, you're limited to 6 users. The Logseq DB version also seems nice, but it's in alpha, so I don't trust it with important data.

https://redd.it/1x46frq
@r_SelfHosted