Short answer: The IDEX card is a FIDO2 security key. It works with services that support FIDO2 security keys – that is, an external key you present, not a passkey stored on the phone or computer itself. Whether a given service works also depends on the platform the user signs in from.
What the service needs to support
Some services support passkeys only as a biometric on the device itself. The card is a separate, external key, so the service has to accept security keys as a sign-in method. In a service's settings this is usually called a security key, a hardware key or an external passkey.
What the platform decides
The same service can behave differently depending on where the user signs in from. sign-in is supported on iPhone over NFC, and on Windows with a reader – many computers have NFC or a smartcard reader built in, otherwise an external reader is needed. See: Platform support for sign-in and Smartcard readers for Windows.
Checking a service yourself
Register the card with the service, sign out, and sign back in with it. Completing the full cycle is a good way to confirm compatibility. See: Test your card's FIDO2 function and Register the card with a service.
Questions about a specific service
If you are unsure whether a service or platform will work in your setup, contact us and we will help you find out.