BSLegacyLauncher VS bnetlauncher

You mean like with Legacy Launcher? https://github.com/RiskiVR/BSLegacyLauncher

Mods aren’t out for the current version yet so you’ll have to use bslegacy which you can download here https://bslegacy.com/ then once you install mod assistant just use the file course for the install (ex: 1.29.0) which can be found in the “installed versions” folder in the same main folder as the bslegacy launcher itself

there is also a client that makes a new instance of beat saber and is a little easier to use, but it wont track your hours https://bslegacy.com/

You can use BSlegacy launcher to have access to older versions without changing your original steam version. I have used 1.27, 1.28 and 1.29 on BSlegacy launcher https://bslegacy.com/

You can use BSlegacy to downgrade your beat saber version to whatever you'd like.

Use update skipper and stay on older versions. If you already updated you can use legacy launcher to install older versions. You can also manually install old mods into your mod folder, but this wont always work.

download the oculus store downgrader from this site https://bslegacy.com/

Ive used this in the past connecting battle.net games to Steam (To play with steam controller)

Login and bypass the launcher? I found this utility for Windows. But it does not work on steam deck.

This utility works on Windows but unfortunately I can not get it to work on Steam Deck.

For my note: https://github.com/dafzor/bnetlauncher/issues/13

After looking around a bit I found this shortcut launcher on GitHub. Might be better for you. It's basically an .exe that you give arguments to launch battle.net games.

Try this