You don't necessarily want free software and traditional cryptography for such use cases.

The traditional free software approach to cryptography is "derive the key from a passphrase; require the user to make the passphrase strong; if the passphrase is weak, put the onus on the user."

This works well for HNers, but is terrible for normies. What normal users want is a locked down chip (potentially running open source firmware!), which securely stores something like an AES key protected by a 6-digit pin, which gets erased after 10 unsuccessful attempts and cannot be cloned. This is how TPMs, Apple's secure enclaves and bank and SIM cards work. This kind of design did more to bring full-disk encryption to end users than any free software ever did.