I find sometimes installing a bunch of different DEs can cause weird cross-issues, so I tend to just make VMs to try out new things. I have a bunch of them on an external drive like little specimen jars lol.

Also as a side note, I keep a VM that’s as close to my current setup as possible, so if I get the urge to try something weird I can do it there first and see if it breaks anything.

You can install them like any other package from dnf/apt and then run them with startX (if its X11) or start them via their name if they are Wayland compositors (all this in the tty, the black screen with just letter outputs)

Not sure about others but in PopOS (and I assume Ubuntu) it’s pretty simple. Probably easy with most distros.

apt install gnome-desktop
apt install kde-standard
apt install xubuntu-desktop
apt install cinnamon-desktop-environment
apt install xfce4 xfce4-goodies
etc.

Why not install a live disc type image to USB and try out different varieties? Linux Mint offers three live images with Cinnamon, MATE, and XFCE.

I quickly found this article on installing them to USB: https://itsfoss.com/linux-mint-live-usb/

Many popular distributions offer live images so you can try before installation.

Usually when you have multiple DEs installed, the login manager would let you choose.

Just need to make sure the autologin don’t get in the way of your choice (e.g. select it thru autologin or disable it completely).

Maybe this will help https://github.com/89luca89/distrobox

You could use https://netboot.xyz/ to boot a bunch of Live systems from various distros relatively quickly (depending on your download speed).

therr are utilities to install lots of isos ona live usb, flash distros that use the des that uou wanna try and you can hotswap them

You can use live isos. Some distros, such as Manjaro or Fedora spins, has several isos, one per DE.

Grab live cd and run it in qemu:

qemu-system-x86_64 -enable-kvm -machine type=pc \
-cpu host -smp 2 \
-m 4096 -device virtio-balloon \
-vga virtio -display sdl,gl=on \
-usb -device usb-tablet \
-boot d -cdrom "$@"

Maybe it will be best to give up right now and use GNOME. I hate it, but let’s be honest most of the time people are running KDE and others will end up with a bunch of GNOME/GTK/libadwaita components and creating a Frankenstein of a system because some specific App depends on said components.

There’s no point on running anything else if you’ll end up with parts of GNOME and inconsistencies all over the place.

Well, if you are new to Linux, it is better if you just install new distros to try them, I would go to Arch Linux as it’s the cleanest distro, I could install multiple DE without issues, but then it’s a bit mess of packages, also it’s harder to install, you need to type archinstall and understand their options. I have a desktop and laptop and I always use the laptop for testing, if you copy the ~/.config folder, you can restore all your applications settings (just copy the app settings you are using), ~/.mozilla to restore your browser as you had it before the wipe and some more settings are under ~/.local. I also copy my ~/.zshrc because I have a custom prompt, configs, add-ons, alias…