Pico C/C++ SDK library for MFRC522.
Tested with this RC522 module: https://www.az-delivery.de/en/products/rfid-set.
Based on the arduino library for MFRC522 https://github.com/miguelbalboa/rfid. Modified the library by https://github.com/luisfg30/rfid so that it works for the Pico. See those projects for more information.
Datasheet: https://www.nxp.com/docs/en/data-sheet/MFRC522.pdf