Controller support in addition to deck itself?

having a hard time finding an answer to this question. is it possible to have someone play on the steam deck itself and a co-op player use a controller. I.e a ps5 one.

My friend has a steam deck and i wanted to surprise them by suggesting we play some binding of issac or some sort of co-op game like that while we're on the train soon. Busting out a controller to pair. They'd probably want to play on the deck itself, but i dont know if thats possible. If its just exclusively multiple controllers can be used OR just the steam deck itself.