When you install a game with Game Pass you can tell it what drive to install to. I think by default it might just install to your windows system drive but you can toggle that option in tho settings.

I installed Starfield to my F drive so it’s installed into something like: F:/XboxGames/Starfield. I then installed Vortex. Vortex did not automatically detect it but I just hit the button to manage it manually and directed Vortex to my F:/XboxGames/Starfield/Content directory… then it picked it up and I can install and deploy mods to it just like I can Skyrim or Fallout (which I have through Steam)