A positive aspect of Discord is that it makes Matrix look less terrible.

#syncthing is a really good file-synchronisation tool. I've been using it for years and it's done it job well without feature creep or any crap.

It's even got a user-friendly interface for setting up synced directories.

If you're not familiar, I highly recommend this article by @nikitonsky:

https://tonsky.me/blog/syncthing/