Create a custom login flow

I have a question regarding whether or not a particular authentication flow is supported

in short, in addition to the obviously supported standard ways of user login that is supported by auth0, I want to offer a ‘custom’ way for users to log into my app. This way is roughly as follows:

on account creation user provides my server with a cryptographic public key. I store this public key in my apps database and create a user entry for them in Auth0

when the user wants to login, they go to a particular login page that I have created which prompts them to cryptographically sign a piece of data with the private key they used to generate the public key they sent on account creation

My server then verifies that the piece of data has been signed correctly using the public key in the db and then my server asks Auth0 to issue an ID token / jwt token for the user.

I have read through some of the docs and there are some flows that might suit this use case I think but I cannot be sure.

anyone have any thoughts?