An alternative to Kubuntu is TuxedoOS (similar to PopOS (Gnome) but for KDE). You can also try KDE Neon.
You can use VM to install and try new distro, worst case you make a new VM and start again.
For learning, if it was me I would just roll with Arch, using distro like Garuda that has BTRFS rollback or even EndeavourOS. A fuck up can be saved from BTRFS rollback, back up dual boost or 2nd pc.