Discord's not going away, but I looked at setting up a self hosted matrix server last night and had it up with an element client in 20 minutes with docker compose. I don't think I'll do a discord<->matrix bridge (since it requires extra stuff on the discord side and I think you lose encryption, which isn't that important), but if you have buddies who you want to keep in contact with, it's not a bad solution

I explored but am avoiding big, public channels because there honestly isn't that much chatting going on in the ones that I found