Stoat (formerly known as Revolt) is a selfhostable, FOSS replacement for discord [Group chats and voice channels you can join any time].
Cool new name, however not as easy to use in other languages.
Voice chat is stil not officialy implemented.
Self-hosting there. Apparently nothing to do for you if you had already hosted before the name change.
The Android app has unfortunately disappeared (not been updated) on F-droid.
Edit: added short description for clarification
You mean the multiple millions of VC money and crypto investments? Absolutely.
The Matrix foundation also would have plenty of money if it wasn’t just a front for Element and most funds being siphoned off to pay for services provided by Element.