TOKEN2 Companion app is a tool to leverage the use of TOKEN2 FIDO2 security keys (second-generation only, T2F2-ALU, and T2F2-NFC) beyond classic U2F and standard FIDO2/WebAuthn functionality. The app enables you to set and use TOTP profiles on a Windows machine.
As the FIDO2 security keys do not have a system clock nor a display, they cannot be used as standalone TOTP tokens. However, you can save TOTP profiles on your T2F2-ALU and T2F2-NFC security keys and retrieve the generated OTPs via the companion app. This will allow using the same device for your FIDO2 and TOTP protected accounts (i.e. use the same key for Azure Passwordless and Azure MFA login).