It seems to me that you’ll have to install the whole Bazzite distro to enjoy its goodies. If we’re only talking about running Steam, I’d just go with Flatpak for an easy start.

From my very non-scientific tests on an AMD 6800U device, running steam via Bazzite + distrobox gave me a 0-2fps boost versus running steam on uBlue Kinoite with Flatpak. Mangohud was slightly easier to manage with Bazzite’s distrobox setup. I did not test power consumption between the two for mobile gaming.

Debian schroot in a distro. Give the user in the schroot access to the snd device. Install Steam in the schroot. There, done. It’s even portable.

Flatpak is as good as native. I switched from native to flatpak with no perf differences