In case you missed it, there's a free open Fediverse alternative to Reddit under construction called Prismo:
You can try the first instance at:https://prismo.xyzhttps://prismo.xyz/auth/sign_up
The idea is that each instance is the equivalent of a subreddit, dedicated to a particular topic.
Prismo federates with ActivityPub so you can follow Prismo accounts from Mastodon etc. (The federation isn't completed yet though, so some features are missing.)