Does the GT-521F52 fingerprint sensor need to support downloading and uploading fingerprint templates between multiple devices (template synchronization), or is local fingerprint verification on each device sufficient?
It is local by default, though in theory you could use an MCU that has wifi and pass the database to a central location - see the examples here Fingerprint Scanner (GT-521Fxx) Hookup Guide - SparkFun Learn
We don’t have an example for such, but in theory as long as the board supports OTA updates you could update the central database then pass it to the other MCUs + fingerprint scanners