Yeah it’s so odd that none of the open-source alternatives have this feature. No video calls are not an option. We need video/voice rooms!
You might be interested in https://kloak.app I believe. It's a privacy-first alternative. It's still in early alpha days, but have most of the things set up. Oh, and we’ve got voice channels with screen sharing in beta too.
Aside from Discord, nobody has gotten this right since Yahoo! Live and Tinychat. Both are dead.
If an option doesn't have that then it's not a Discord alternative for me or many of my friends.