Don't have a steamdeck, I did know you can charge stuff off it though. Idk about you, but I often forget to charge my buds, and forget things like my external battery or cables(or the buds themselves) at home as I run out the door.
I wasn't saying that these scenarios would be a daily occurrence, but I can definitely remember enough times that I'd have to count on both hands I've seen someone making a call on the bus with a phablet or tablet. And maybe where you live people have enough respect for the people around them, but every city I've ever lived there's someone talking really loud on speaker about something they really shouldn't be at least once a month that I personally encounter.