The FIDO2 functionality of the NK3 is compatible with Android, whether a PIN is required during an NFC operation is to be defined by the Webauthn Server itself (the website). As far as I know the FIDO2 Specification defines a "user presence" as the required confirmation for the NFC operation (in contrast to entering the PIN), which is the fact that one has to place the NK3 near the NFC sensor of a smartphone and not necessarily the PIN entry.