Bazzite offers KDE or GNOME, and in the menu mentions KDE is what is used in SteamOS.

I installed Bazzite on my HTPC recently. It was the worst install process I've seen in over ten years of using Linux. I shall enumerate the problems I had:

1. The image is weirdly large, it's like 9GB in size. It takes awhile to download and a weirdly long time to write to a USB stick.
2. Once written, you boot the image, and GRUB has the options to Install Bazzite or Test Media And Install Bazzite. By default, Test Media is selected. It always fails this test.
3. If you use the typical non-live environment image, the scaling is tiny on a 4k monitor, and there's no way to adjust this.
4. If you use the live environment image (in beta at time of writing), it might just lock up. I had that happen twice just while clicking through the Anaconda installer.
5. The Anaconda installer, which I think they inherited from Fedora, was I think designed by one of the contrarian idiots who work for Gnome. There's a DONE button up in the far upper left hand corner of the screen that sometimes acts as a back button, sometimes acts as a forward button. You have to move the mouse from the top corner of the screen to the center of the screen a lot, for no reason. The top-left corner of the screen is a dumb place to put a DONE button because most languages read top to bottom, left to right, the DONE button is where a START button should go.
6. There isn't a simple way to tell it "put / on this drive, put /home on that drive." There's an automatic installer which will do god knows what...fail, most likely. There's a "custom" partition dialog which I couldn't make heads or tails of, and then there's a "custom advanced" one that lets you set the size and position of each partition to the byte. Doing it this way apparently REQUIRES you to not only set up a /boot/efi partition, but also a /boot partition separate from /root.
7. If you're in the habit of putting /, you know, operating system and software, on one drive, and /home on another drive, you have to learn from osmosis that part of Bazzite's immutableness means that there is no /home, there's a /var/home symlinked to /home.

And if it doesn't randomly lock up, you've got Bazzite installed!

Bazzite markets itself as a newbie friendly Linux. They've got that configurator on their website that gives you a little Cosmo quiz about what system you have, what desktop you want etc. which is good! That is good user friendly design. But the actual software you get rattles like a Chrysler. How many noobs are going to bounce right off that?