They’ve been building an entire open source suite of software tailored to their needs. If I had to guess, Jitsi isn’t performant enough for large (100+) user meetings in a way they can scale easily. It’s a great tool, but it seems better geared towards smaller loads. Video conferencing at scale is a pretty big challenge.

Between this, their new Docs platform and some Matrix-based chat platforms, I think this is something they’ve put a fair bit of thought into how they want to build. Overall, it’s a cool initiative, but I think it’s pretty clear that it’s open source as a means to be transparent as a government organization rather than to form a platform for broad use by everyone. They do have some self-hosting instructions on their GitHub though.