I think it's pretty doable, but there are some things you should think about:
- Email delivery dependencies: If you use email addresses on the domains you're hosting, problems in DNS will cause you to not be able to receive emails. This can be a problem if you plan on monitoring your DNS with alerts via email, or if you need to do password recovery via email to access your VPS accounts, for example. Check if this applies to other services you might be running.
- You'll need to understand glue records to setup at least one of your domains.
For my domains, I'm running nsd in two different VPSes, and the way that I edit my zones is that I have a script that converts a shorthand format (that I came up with) to a standard zone file and then rsyncs (using hostnames declared in my .ssh/config files) the zone files and nsd configuration files to both servers. The script then reloads nsd.
I chose nsd because it felt like the simpler option, no troubles so far. I use them directly on my debian hosts, no containers.
I have no monitoring, but I should. My terrible excuse is that the infrastructure I'm running is not critical and it's on the same hosts as my nameservers, so they usually go down together. I wouldn't put client domain names in there without monitoring.
owncast is more of a "stream one thing to multiple viewers" kind of thing, as opposed to Jitsi which is more for meetings.
I've used owncast to host a couple of conferences, set it up on Linode with their single click install thing, I think. We had a jitsi call for the round table and one of the participants had OBS streamings its jitsi window to owncast. For individual presentations, we used https://vdo.ninja/ to get the presenters screen/camera/microphone onto OBS, where it was muxed and streamed to owncast.