Just write it down. Paper, steel, whatever, just don’t store it digitally. If you’re storing something worth more than a hardware wallet, the seed with a good hardware wallet is a good idea. Memorize it if you can, but have it written down somewhere. If you can rip wireless networking out of a device, airgapped notebook or cell phone is fine. If you have a bunch of different people that will need access in the event you can’t give them access, and you’re concerned about one of them potentially stealing it from you, and they know how to do this kind of stuff, shamir backup is great.