I have been wondering.. why not using just a toml print and parsing it with OCR?
Today I shill an old project of mine, unrelated to Nostr: https://github.com/dtonon/papiro
Papiro is a very simple tool for storing any data in physical form by printing qrcodes on one or more pages. I created it a couple of years ago for a personal need; maybe it can be useful to you too to improve your backup strategy. Try it :)
Why QR Codes on paper?Because paper seems the most resilient and cost-effective storage medium on earth, at least for low volume data, and QR Codes have an interesting error-checking system. So it is a nice backup solution to pair with digital ones.
Discussion
Because toml is not suited for binary data and does not support error correction.
(I guess)
It would be a custom OCR to optimise it for specifically this format, as already existing OCRs are "too smart" as they expect more than just a TOML.
For the QR Code, any scanner is already optimised to the specifics of a QR Code. QR Codes always look & work the same. No custom engine needed.