There was an interesting Kickstarter a while ago called DiceKeys https://www.crowdsupply.com/dicekeys/dicekeys that provided a physical mechanism to store the seed of a passkey.

If you then purchased passkeys that supported a custom seed, you could then replicate this seed to as many keys as you needed.

There are always security tradeoffs, but this was a mechanism to store something in the real world that had about 115 bits of entropy, as 'Something you know'