If it's code like the OP seems to indicate, publish it on github; many services draw copies of source code from Github, and they themselves once put all code into cold storage for posterity: https://archiveprogram.github.com/arctic-vault/

> Each was packaged as a single TAR file.

> For greater data density and integrity, most data was stored QR-encoded, and compressed.

> A human-readable index and guide found on every reel explains how to recover the data

> The 02/02/2020 snapshot, consisting of 21TB of data, was archived to 186 reels of film by our archive partners Piql and then transported to the Arctic Code Vault, where it resides today.

That's the "pay someone else to do it" option.

It's this way because "archive and then forget about it" isn't really a thing. It turns out an archive that is not maintained is no archive.

Build a pyramid and carve your data into walls deep inside the pyramid.

And then pay somebody to guard it. Aka the "pay someone else to do it" option that your sibling comment talks about (and of which there are many different flavors, S3 being another one).

I'd prefer a mobile solution. Something I can just put into a box and forget about. Someone else can than stumble upon it and be able to read it.

Basically like a box of photographs. But I know that's a foolish dream to have.