The race/flight sim market is still going strong, but I guess it's the exception that proves the rule. It's extremely difficult to make a non-vehicle-based game that actually plays well in VR.
Potentially related, IIUC Unity only has linux arm64 support for the embedded linux version. And to use that you have to contact sales.
https://partner.steamgames.com/doc/steamhardware/steamframe/...