I developed Authorizer to have a cross-platform solution without any server/cloud-service.
It is an offline hardware password manager based on PasswdSafe for Android. The concept is to use an old Android phone as your password manager. It can type the password over USB and Bluetooth on your target device. Supports OTP.
Smartcard and WebAuthn support are on the roadmap. Doing also a lot of modernization on the next weeks. https://github.com/tejado/Authorizer