Thank you for this post, I think it will come in handy. Yesterday I tried the manual installation as I also wanted to integrate it with my existing xmppd (prosody) instead of using the all-in-one Debian package but I gave up when some piece of it required ancient openjdk-7-jre. Is your setup working with openjkd-11-jre?

“Remember to […] stop and disable the bundled prosody! That’s it!”
Do you know if I can prevent it from starting it after installation? I don’t want to risk f*ing up my prosody by installing jitsi.