They can only be used for signing via NFC, as far as I know, and that naturally means you need to have a wallet app that supports signing via NFC. I don't know of any others besides Nunchuk, especially on iOS.

Yeah tested it with Nunchuk, worked pretty sweet. Too bad not too many others support it atm😃

You can pair Tapsigner with Sparrow as well (Desktop NFC reader needed).