How do I combine PC and Mobile?

[TheGriffinator]

I don't see an option that let's me connect my xbox profile to my Fallout Shelter on mobile.

[Help]

https://help.bethesda.net/app/answers/detail/a_id/34950/~/can-i-share-my-fallout-shelter-vaults-between-different-platforms%3F

Q: Can I share my Fallout Shelter Vaults between different platforms?
A: Vaults cannot be shared between platforms (iOS, Android, Bethesda.net Launcher, or Steam). However, you can access the same Vault on platforms that support Xbox Play Anywhere (Xbox One and Universal Windows Platform on Windows 10).

I'm assuming that's via "Microsoft Store" which you can find on your Windows start menu, don't think you can transfer it to Steam for PC.
(which means you need a Windows phone if you want your xbox profile on mobile...)

[Ryuu]

You can't connect, but you can copy savegames
https://steamcommunity.com/sharedfiles/filedetails/?id=893952874
Not sure if it works both ways, don't have an xbox and never plan to

For PC and Android devices it's very possible to establish a sync yourself:
https://steamcommunity.com/app/588430/discussions/0/135513421443113496/
Enjoy digital jail in hardware form.