How is it different from other hardware security thingies you may know?

#Yubikeys don't store passwords and are not open source. They do #2FA, which #Signet does not.

#Nitrokeys store 0 to 16 passwords (depending on the model). Signet can store hundreds of passwords. Nitrokeys do things like email encryption and #FIDO2 (depending on the model), which Signet does not.

The #Trezor Model T does not store passwords. It does FIDO2 and holds your digital currencies.