Most handhelds aren't built with productivity in mind. The Legion Go with its detachable controllers could perhaps make an impromptu work station, but that's the beauty of PC's. People often find use cases that the manufacturer never intended.
The Steam Deck doesn't make the ideal workhorse. By the time you're carrying a separate keyboard and mouse, you're likely better off just packing a laptop. There's no kick stand and running calculations on a 10,000 line spreadsheet isn't going to be fun, let alone on the Deck's paltry 800p screen. But that never stopped the community, and the Deck is certainly capable of bashing out a few emails and a great deal more once you start exploring the broad library of FOSS available under Linux.
If carrying multiple devices isn't your bag, thanks to Natter_LT you can 3D print your own Steam Deck "Play&Work" case for only $9.25.
There are some definite Steam Punk vibes going on with this case, but that only adds to the charm. There are many thoughtful flourishes, like being able to slot in a standard Logitech Pebble Keys 2 K380s (available on Amazon) and making it removable. Cutouts for all the ports and buttons, a carrying handle and a built-in kick stand that opens to allow air flow to the Steam Deck vents. When closed, the entire package seems very similar in size to the case provided by Valve.
If you've got access to a 3D printer with a bed size of at least 300mm squared, the $9.25 for the CAD files seems like great value to be able to create the ultimate portable gaming slash mobile office. If only we could get one for those that aren't packing a Steam Deck.
Source(s)
GameRant, Cults3D, Justinas Jakubovskis (Via YouTube)