I have my HP Windows Mixed Reality headset and a lot of games on Steam and actually, I don't even know whether GOG has VR support, specially WMR.

Might anyone help me out?

I've tried Alice VR and Obduction

Both use the WMR plug in with SteamVR

Fortunately SteamVR will run independent to Steam

Alice VR, starts with you looking the wrong way, (have to look to the left) which makes starting the game a bit of a faff.

Let me see if I got it...when you run a VR game on GOG does SteamVR automatically open and run it?

yep, if the game uses SteamVR it will launch but not launch Steam

Mate, it seems so odd to me, I'll try it out though.

Thanks for your time!

Just wanted to remind you: If mechmouse's advice was helpful, you should mark his post as 'solution' so he can have his uprep reward.

Lots of other Q OP's out there who should do the same.