I miss my GBA, I loved the form factor of that little guy. Fit perfectly in a pocket, super comfortable to hold for ages. I had the see through plastic version which was super cool.
There are so many portable emulators these days in that form factor. It seems like there's at least one new one each month. I've bought and used several from Anbernic personally or as gifts.
Sony has officially supported Linux distros for both PS2 and 3.
However, that's not what the games ran on, so it still fits with your definition. It's just interesting to think about given the current state of things.
If you can select OS, it's PC. If the manufacturer can't even things with exclusive game sales and licensing, hardware would be more expensive than it would be as a console. Sell the hardware cheap, gather profit from games people want to publish on your platform.