May be! No idea what the process is to get there, I’ll take a look
Constellation is deeply connected with COsmos, it uses the Cosmos users for permissions and access, uses the Cosmos reverse proxy to access docker container, etc… so it’s only in a Cosmos server yes
Yes so with the App you can set your domain to point to a Constellation IP, and your site will only be accessible when connected to Constellation with your domain name, hidden away.
This is very cool feature, however if it is not free then I need to look other way. Can I somehow make a tunnel of my own that hides away the domain name, for example OpenZiti or gluetun? I’m new to Cosmos and new to docker, not very good combination 
Excellent job by the way!
Yes you can use any VPN you want with cosmos but you would have to set it up manually, it won’t work with constellation directly