As title says. Obviously I could setup different virtual machines or spend the time and install all the DEs in one VM if it is even possible without breaking the OS. I'm wondering if there is an already made iso or something that installs all the maintained DEs for trying.
This doesn't work well in practice when switching between Gnome and KDE. Both change configuration in /home, which might break theming and results in strange behavior.
Logging in with a different user for each desktop environment does prevent such issues. Or alternatively deleting the right folders in ~/.config should fix it too.
In that case, wouldn't it be possible to try this on any distro? Just make a new user per DE? Also, I think what they're pointing out is that you can change DE and rollback to where you were before
Installing multiple distros at the same time would cause issues because of additional software most DE's come with (image viewer, ...). But yes, it's possible to switch DE by uninstalling the desktop package group and installing another quite easily. Especially with btrfs snapshots it's simple to roll back.
Yes, it's possible to rollback with ublue but that won't roll back changes in the home directory. So if you switched from Gnome to KDE and then back to Gnome the additional configuration from KDE might conflict with Gnome (especially theming breaks easily).