I use Cockpit on isolated Debian Bullseye VM hosts to provide a UI to libvirt.
It's very nice for that - it's minimalist, it doesn't get in the way of anything you want to do manually, and it doesn't wreck your VM configs if you just want to use it as a nice way to get console access.
I tried it on Ubuntu two years ago and it didn't feel very polished. I was able to create virtual machines and inspect basic metrics, but it would throw errors on about half of the features, assumed it was because it was built for RedHat and things were done differently on Ubuntu, or that I had simply done something incompatible in my manual configuration.
Would you say all the features of cockpit work on Debian?
It's very nice for that - it's minimalist, it doesn't get in the way of anything you want to do manually, and it doesn't wreck your VM configs if you just want to use it as a nice way to get console access.
Highly recommend!