If you want to give KDE a shot, you don’t need to buy a Deck. Just grab a live installer image from a Linux distro you like, tons of them let you boot and try it out without installing.

I’m pretty UI agnostic (many years with Windows, Mac, ChromeOS, Unity, a few with xfce, and a bit with Cinnamon). I almost picked Gnome on a recent update to my primary home machine for its clean Mac-ish feel, but SteamOS convinced me that modern KDE is actually rather nice.