In theory you can, in practice Game Pass games are distributed in such a way only Windows can run them. You can use Game Pass Streaming which is fine when at home, and entirely useless when on a train using a Steam Deck.

The ideal would be MS just selling Game Pass subscriptions via Steam but I expect we'll see that happen shortly after hell freezes over.

They can just add an API and let the folks from the Heroic Launcher do the rest.