[1] https://mntmn.com/media/news_md/2019-05-20-reintroducing-ref...
It's a laptop shell (keyboard + screen + battery + i/o) that has a daughter board (connected to the computer via USB and HDMI) and enough space for any reasonable SBC. Comes with Raspberry Pi as standard.
I’m genuinely surprised that this isn’t already a thing, since it would make upgrades trivial.
Android has all of the capabilities software-wise, but I have yet to find a device that matches the Psion Series 5mx form factor, specifically the folding clamshell and nicely-sized hardware keyboard.
Most external foldable Bluetooth keyboards are too big, rather finicky, and always running out of battery on me.