TrueCrypt had/has that feature for full-drive encryption. But I don’t think anyone serious uses them anymore due to the current code maintainers having some questionable allegiances.

Not sure if you count nonprofits, but the Braille Institute has Atkinson Hyperlegible

Add to that the capability of Meshtastic to do basic encryption and a device entry fee of <$15. Limited scope doesnt matter as much if it’s widespread enough.

You could also get one of the SSD drives that look like flash storage. I got a “usb stick” with 512GB SSD for about $60 last year.

I’m trying to get back into HAM after 30 years out of it. Starting with meshtastic let’s me play around without spending a lot on hardware, and before I get my license back.

There are great prebuilt nodes for under $50, and as low as $20 if you build your own from parts.