It is an FPGA, fully open both at software and hardware level. So quite a bit more futurproof, inspectable and upgradable than a yubikey.
It also perform a measurement of the application being loaded. And the measurement together with the Unique Device Secret (UDS) will generate the primary secret applications can use to derive keys etc it needs. This means that you can verify the application integrity.
This is very close to, inspired by DICE: https://www.microsoft.com/en-us/research/project/dice-device...
You can additionally supply a secret from the host (the User Supplied Secret). This means that the keys generated are tied to the specific device (the UDS), that the integrity of the application is correct, and to you as a user.