#You are perfectly right.
All major distributions offer all major Environments. I currently use either Debian or Ubuntu and usually install by booting the Netinstall.iso right from the official Servers which installs just the base system without any GUI at all. Then I use tasksel to select the environment. Ok, not every Environment is part of Tasksel but often it is just adding another Repository and running another apt install operation.
And yes, on my experimental computer I often install a dozen environments just because I can. Selectable at Login-Screen.
But now somethings VERY important from someone with 35 years of POSIX experience:
If you are a newby FOR GODS SAKE USE UBUNTU.
And if you are a pro… Ubuntu still is a very good option. Only if your have VERY GOOD REASONS which you COMPLETELY UNDERSTAND, only then use something else. Which is Debian for me.
PopOS is a sure way of getting into ten times more problems than Ubuntu.
Seriously, I know them all. Started with NetBSD in 1991, used pretty much everything.
If your system isn’t super weird then Ubuntu is the most relaxed experience you will ever have as a newby.
(And yes, I am not using Ubuntu currently. But then, I hat 35 years of POSIX/Unix/Linux experience)