I’m using this portable monitor but it is kind of finicky, and I worry it’ll break easily. It’s the biggest one I could find at a reasonable price, and happens to fit my backpack.

I’ve used it with my 3440x1440 freesync monitor at home, and it works as well, but like anything, whether you can game at that resolution is very dependant on the specific game and settings you use.

I’ll add, because the deck doesn’t have thunderbolt, plan on using HDMI instead of type c. It’s possible you can find a type c (non-thunderbolt) dock that supports powering and driving a monitor over type c along with the deck, but I wasn’t able to find one.