About Using my xbox game pass for pc in another country?

if it's not available, you'll simply won't be able to use it.

yes, as long as the service is available in the country, remember that your account is linked in the cloud so you should have no problem

you can use it, just change the region.But some games might not be available.

What if the service is not available in the country?

As long as you keep your region set to where you physically are, and where your Xbox is, you should be fine. You should be able to change it to Pakistan and when you load any games, it will sync the saves from the Cloud so you will not have lost anything.
Just make sure when you return to Saudi Arabia, you switch it back to that region. Good luck!