So this is slightly off topic for RFID implants but I know a fair few people who have talked about these.
The hunter cat NFC has been released and we’re waiting for stock to arrive.
They are an NFC version of the original hunter cat and detect EMV Card cloning attacks, NFC reading/writing but also peer to peer connections.
https://labs.ksec.co.uk/product/hunter-cat-nfc/
You can find the original hunter cat here, this detects Magstripe cloning attempts on payment cards:
https://labs.ksec.co.uk/product/hunter-cat-card-skimmer-detector/