To complement Steven's answer, Trezor can be use in PoS, it would just require them to run a Bitcoin wallet which they most likely already do!

The Trezor wallet give them your public key, then the PoS creates the transaction and send it back to your Trezor for signing. After verifying the output address & amount and entering your pin on the Trezor it will sign the transaction and send it back to the PoS who will be able to advertise it.

The Trezor works with USB, but in next versions you could certainly use other communications methods like NFC or BLE... Also since the software is open-source it calls for other hardware wallets to use the same wire protocol and make is a de facto standard for PoS transactions involving hardware wallets.

To complement Steven's answer, Trezor can be used in PoS, it would just require them to run a Bitcoin wallet which they most likely already do!

The Trezor wallet give them your public key, then the PoS creates the transaction and send it back to your Trezor for signing. After verifying the output address & amount and entering your pin on the Trezor it will sign the transaction and send it back to the PoS who will be able to advertise it.

The Trezor works with USB, but in future versions it could certainly use other communications methods like NFC or BLE... Also since the software is open-source it calls for other hardware wallets to use the same wire protocol and make it a de facto standard for PoS transactions involving hardware wallets.