I believe I understand what you want. "Zero" login. So when a user comes to your site or first boots up your app a private key gets generated locally. It will then do a handshake with the server, where that the server understands that these encrypted messages are from this user, this uniquely identifies the user, and also can be used for e2e.
Reference https://dev.to/spalladino/a-beginners-intro-to-coding-zero-knowledge-proofs-c56
I've been doing the same thing with larger containers of plain Greek yogurt. Some frozen fruit mixed in. No added sugar just as good way cheaper.