I just found something that is extremely up-my-alley. This is a ruggedized IBM PC-compatible handheld computer that runs off 4 AA batteries.
And it has real keyboard, no windows keys. That was good find as they are hard to come by even when new.
Also, booting DOS from ROM has something appealing. And its all in a self-contained unit. Actually quite well contained. Notably, there had been also a 80 columns version, the Husky Hunter 16/80. (These machines are as close as you may get me fancying DOS. )
As far as I recall from some other articles/videos, there’s a trick for cold starting. So, while a machine may appear to be broken, it may actual work perfectly if you follow the cold start procedures correctly.
BTW, the original Husky Hunter (1984) was a Z80 machine, featuring a CP/M 2.2 compatible DEMOS operating system and a powerful BASIC.
And before this, there was the more humble Husky (1981), a BASIC machine using a membrane keyboard (apparently, what was good enough for the ZX-81, was good for the British Army, as well): https://www.old-computers.com/museum/computer.asp?c=471
And here’s a page on the Husky Hunter 2 (still Z80-based, 128KB–726KB):
And another one:
(This page features a download link for the PC-based communication software HCOM.)