TeamTalk5, a free, self-hosted conferencing system with high-quality audio

Interesting alternative. But on prima facie, its GUI is several years dated and there's no web client which is a significant disqualifying factor for most users comparing against the likes of Zoom, Hangouts, Skype and Jitsi.

While I'm impressed that its GUI client isn't Electron which some clients burn up my MacBook and it can be self hosted, it is not enough to attract users to use this without a 1-click create and join meeting functionality like what the rest of the competition has done.

I think I'll skip this for now.

Not free for self-hosted at all: "Building a TeamTalk 5 server requires TeamTalk 5 Professional Edition."

You don't have to build it though. Binaries are available for download.

This is the business model of TT. Standard functionality is available for free, but if you want to build custom workflows for it, you need to pay.

Yes team speak with video rooms and collaboration tools.