You are most definitely running Discord in XWayland. You need to add chromium flags to make it run in native Wayland. You also need to have an xdg desktop portal to support screen sharing.

If you want screenshare to work on an app that can’t run in wayland, use XWaylandVideoBridge

Yea you can.

I’m pretty sure the website is mostly directed at distro maintainers, to not force a custom theme on users. They’re fine with users tinkering on their own.

Not much. I have a searxng instance, used to have nextcloud… I should start hosting more stuff really soon