Are you using GOG games on your Steam Deck?

A couple games popped up on my Steam wishlist at really low prices so I was thinking of getting them, but I’ve also had a few older computers recently that are losing Steam client support. This got me thinking I should really try to compare and get more games on GOG so it doesn’t matter if a client stops working on older hardware. But also following this community has had me thinking a Steam Deck makes a lot of sense for me, so maybe I’ll try to get one in the next year or two. It seems like Steam tries to keep things open to other sources on the device, but have you been playing non-Steam games, and how much hassle has it been?

Also the games I was considering are Donut County and Planet Coaster, if you have any thoughts on those.