Screw that not even Google knows how I look like (I don't take selfies or upload photos of myself nor does my family) so I'm not about to let some message app link my identity to my internet account.
Here's the write up they have over on Reset Era on their Alternative Apps/Software Thread:
Stoat -
Previously Revolt. I would consider it the best Discord alternative available right now. It lacks federation which I feel is a missed opportunity.
Spacebar - Free and open source, full stack reverse engineering and re-implementation of Discord. This is more acceptable to me as it's literally just meant to be self-hostable Discord.
Matrix - Same stuff as in the instant messaging section. It often gets mentioned but it's only a somewhat viable alternative. If you only use it for chat then the Discord bridge works really well but takes some set up. I recommend the in development
Commet app if you want the Discord experience.
Commune - It's aiming to be the de-facto fediverse discord alternative. It builds on Matrix and combines with ActivityPub to get the best of both worlds. It's early in development but it's a very interesting idea.
Polyphony - An in development attempt at a federated Discord alternative using the in-house (I think)
polyproto protocol. Compatible with Discord's API so it's also interoperable with Spacebar (and more importantly Discord itself I believe) so you can continue communicating with people who remain on those services.