Fubarberry already posted a SteamDeckHQ article about this but I wanted to highlight the direct sources.
Per Valve in their Steam Machine FAQ:
If I don’t get a Steam Machine right away, is there anything else I can do?
Thanks to the openness of the PC platform, there are lots of options for devices that will allow you to run games natively or streamed to your TV. There are many PC sites and communities out there that can help you with that. For our part, we are continuing to work toward enabling SteamOS to be used on more hardware than just ours. In fact, with the newly-released SteamOS 3.8, you can run the same code and operating system as Steam Machine on your own living-room PC using whatever PC parts you want: learn more here. Right now, only AMD GPUs are supported, but we’re working on expanding support for the future.
The single biggest advantage of Bazzite over SteamOS is that it has the option to install programs from the normal software repos. If something you need isn’t available as a flatpak/appimage/etc, you can install it anyways to a package layer, and it will be available after a reboot. This is also really nice for programs that need better system integration, for example getting a flatpak password manager to integrate with a flatpak web browser often doesn’t work.