Thanks, interesting to hear that you have no issues with 3 different headsets.
Re launcher I have tried from the .exe directly or from the Origin app. Yes, I confirm all my other games use the SteamVR runtime.
There is definitely no issue with objects in my play area or cameras, as I swap straight from Automobilista or MSFS into F1 and consistently have no problems in the other games and the same problems in F1.
I think FOV was a bad choice of term from me - to clarify I am not talking about changing the Oculus Debug FOV (indeed I run at 100% in Link or via Virtual Desktop which is my preference), it was more my attempt to describe the strange camera movement I perceive on head turn. It gives me an almost small Dolly Zoom effect (eg https://www.youtube.com/watch?v=_OO3pqJVLAc&ab_channel=MKArtStudio) which led me to question whether there was an incorrect IPD, FOV or Zoom setting in the game. This evening I will again reset my Steam settings and confirm no change to Steam FOV.
In my testing I did also play with the xml including the 2 lines you mentioned, but will try again this evening and report back. Thanks for trying to assist !