I agree with other commenters here. For a long time offline secret that needs to derive an encryption key, the solution is a longer passphrase. Diceware is fair

I agree with other commenters here. For a long time offline secret that needs to derive an encryption key, the solution is a longer passphrase. Diceware is fairly able to make passwords that are pretty strong. A 6 word Diceware with no additional complexity like separators or capitalisation is already 77 bits of entropy. 10 words is approx 128 bits.