If you ever wanna try again you could give betacraft launcher a try, it’s specifically for playing alpha/beta versions.
Btw steredenn is even Linux natively, that’s what made me even more angry.
That’s basically the issue… especially older Linux ports run worse than the Windows version. I hope Valve will eventually consider setting Proton as the default for some games even when they are native, as their ports are usually abandoned and outdated.
Moonlight also still builds for it, you can get it from their GitHub, extract it to a fat32 usb drive and boot the Steam Link with it connected.