I know Bazzite is the deck build for HTPC, and is in testing right now for the next updates.

Eh... not quite sure what exactly you are trying to say, but:

Bazzite has multiple variants, and they have a webpage that points you at the correct one.

https://bazzite.gg/#image-picker

There is also the FAQ:

https://docs.bazzite.gg/General/FAQ/

What Bazzite image do I use?

Bazzite's website offers a streamlined way of selecting the correct image which will be chosen based on hardware, desktop environment, and to include Steam Gaming Mode if the hardware supports it.

Bazzite offers multiple images, but most images will be following one of these three variants:

Variant 1: Bazzite images that do not have Steam Gaming Mode and receive automatic updates daily with gaming packages pre-installed.

Variant 2: Bazzite images that automatically boot into Steam Gaming Mode (like SteamOS) and are intended for controller-oriented setups.

Variant 3: Bazzite images that are intended for software development.

... anyway, as others have said, there are actually a lot of differences between Bazzite and SteamOS.

Honestly just read all of the FAQ page.