https://youtu.be/b6xeOLjeKs0?si=sDBTe7CCKxoT5-k5
https://youtu.be/ev0Ay1m4MWs?si=OFprAycQpipTXaTP
Long story short they turn songs into digital fingerprints, where it can be stored in a tiny way. When you start recording you’re making a fingerprint as well. Then it just starts testing yours against its database.
Just don’t connect it to the internet and it’s a dumb display, simple as that