My Ajazz AKP846 just arrived and it is gloriously dumb but I love it. Of course it isn’t an actual computer, it is a keyboard with a touchscreen grafted to the top of it but you can use it just fine with an SBC, it is kind of nifty and fits well with all the other weird little devices.
I say full size because it is actually a fair bit wider than those early portables, compared to my Amstrad NC100 at least. The screen/touch controller alone is probably order of magnitudes more powerful than the processors in those.
Really what I’m pointing out is that this is a modern device using many off the shelf parts and therefore is quite literally what a full sized DevTerm type computer could be if you could integrate some of the guts into the chassis. The only thing missing from the basic design is the built-in mouse.
Think of the amount of battery you could put inside something the size of that Tandy computer with a CM4 running everything. It could last for days.