Gamepass games are on windows store and work through it.
It's why the thing fecking sucks on PC and I cancelled mine.
I can't believe how badly designed it is. I had to change the motherboard on the PC so decided to do a reset of Windows after putting it in. I copied everything to a secondary drive (which the GamePass games were on) to back everything up first.
Everything went smoothly for every app. All I had to do after Windows installed was point Steam and the Epic Game Store to the correct location on the drive. The Xbox App however was a bit different. First there's no way to point to existing game installations so you have to start from scratch. Second, you can't actually remove the already installed games as even admin access doesn't give you authority to delete them meaning I had 400gb of space used up I could do nothing with.
I ended up having to copy everything I could off and format the second drive just because of the Xbox app. It's so bad.
Anyway, MS Flight Simulator. If it's on GamePass that's great as I'm subscribed through to September.