This is used heavily by hardware tokens like Yubikeys, and especially for cryptocurrency people with so called "hardware wallets" like Trezor and Ledger (which

This is used heavily by hardware tokens like Yubikeys, and especially for cryptocurrency people with so called "hardware wallets" like Trezor and Ledger (which can generate many subkeys on the devices). Companies like Google now have employees issues with Yubikeys [1]. [1] https://www.yubico.com/resources/reference-customers/google/ https://www.yubico.com/resources/reference-customers/google/