What would you be able to do with the headset aside from connect it to Steam? They could add support for OpenXR but OpenXR is just starting to get traction and that's on the application developer side. I don't know how widespread the adoption of the HMD agnostic bits of OpenXR are.
On the developer side, both Godot and Unity have some support for VR.
On the game side, there's also Windows MR, which supports some games. I don't know if this headset supports it now, but it could presumably be made to.
Godot and Unity have support for specific VR API's.
This headset is designed for SteamVR.
You can build for this headset by targeting SteamVR in Godot and Unity, but you'd have to do a TON of work yourself if you wanted to build your own VR runtime to bypass SteamVR for use on this headset.
But to use it without steam you would have to develop VR software for your desktop. I think there is some open source stuff but idk how well it works. The PC software end is a much bigger job than the hmd.
However, I can see where the idea would come from, because they do talk a lot about Steam on the site.