The Steamdeck is made by Valve also known as Steam. SteamOS is a Linux based system so it can also run emulators. Valve is also developing a Steam machine, which they had earlier but dropped for some time but are bringing it back again. The Steamdeck and steam machine are basically consoles running on Linux. SteamOS is far more friendlier than some other Linux distributions.
I have a Steamdeck and it is awesome. I bought the OLED version and bought that over the Switch. I have used it a few times for some long flights. I was able to use mine for a flight from London to Phoenix and only had to use a power bank about halfway through the flight. Can go for the whole flight without needing a charge but I didn't put it in battery saving mode.
It is fairly easy to add Netflix and other streaming apps. The SteamOS is rather user friendly and there are a lot of user guides to follow if you get stuck. The one thing I do warn about the steam deck is that if you get an older version of the software there is an issue with it connecting to WiFi but I bought the docking station which solves for that issue as you can use an ethernet cord to a router and connect that way and update the software so it can recognize the WiFi. I think they have fixed this issue already and the stock software is newer and connects to WiFi easier. Though I do still prefer the docking station as it made it easier to watch movies and shows on the screen.
There are only a few games that I have played on the Steamdeck X4 and Baldurs Gate 3. Most I don't like playing on the Steamdeck as the controls can get a bit funky so I only play the ones where I don't have to do all that much.
https://store.steampowered.com/steamdeck?tab=2