That gets me wondering... what would be the ideal here? I don't have much experience with blind-oriented usage but I get the impression blind users only keep screens around for when software/the OS falls apart and orientational cues completely break down... but perhaps sighted assistance is needed less often than I presume, and blind users simply use phones and laptops with screens because that's what dominates the market.

Maybe you could viably get away with having a quick-access mechanism that lets someone use their own device's display whenever assistance is required. I can totally see a device that serves VNC over HTML5 to any web browser via a built-in hotspot, that would be pretty universal.

Which leads me to the question of how useful touchscreen gestures are - since that's all touchscreens are useful for in a blind context - and if there isn't a better input method than that. I get the impression keyboards are pretty much "it". It would be pretty cool if your entire computer was a keyboard with a 3.5mm headphone jack :)

The Pinetab is basically a highish-end ARM system with its own bits of novel hardware added on, so the base question becomes "how usable is the mainline AArch64 Linux experience for blind users?". I suspect it's somewhere between "poor" and "fair"; and bespoke hardware in this device may add a small amount of extra strain on top of that.

Now I'm puzzling over which mechanical keyboards are the thinnest, and if you could cram a power bank and ARM development board into the footprint space underneath.

These OSes are touch-optimized and recommended:

UBPorts (community-driven Ubuntu Touch)

postmarketOS

Arch Linux ARM

I know that desktop Ubuntu has screen reader (Orca) installed by default. No sure about Ubuntu Touch. My Google-fu shows very outdated answers.