Re-inventing the wheel calls for a lot more than usually anticipated. Best to keep it simple - and if you do end up innovating might as well open source it or contribute to an already popular OS solution.
You could use ShowHN in the title for wider reach.
Also, checkout: https://github.com/supertokens/ (might help with building MFA and for building a couple of other auth solutions)
I think it depends entirely on your use case. If the user isn't storing a lot of info in your app then passwordless is the way to go.
Also, important to recognise that replacing a password with a different single factor does not enable passwordless as used by most enterprise companies. Passwordless implies two factor, with both factors not including a password.
Been using this passwordless login recipe by supertokens for my recent projects: https://supertokens.com/docs/passwordless/introduction
Re-inventing the wheel calls for a lot more than usually anticipated. Best to keep it simple - and if you do end up innovating might as well open source it or contribute to an already popular OS solution.