Multiple users for Machine to Machine applications

We do have a dashboard that our customers can use.
By this do you mean creating an Application in Auth0 on a per customer/merchant basis?
I would’ve expected to have one single Auth0 application where all customers/merchants can authenticate to without having to create an Auth0 Application for them. Does this make sense?

What specific thing is hard about this just to make sure I understand?

Regarding your alternative approach, how would you do this if we already have a customer dashboard? Would we have to create a user with Username-Password-Authentication permissions and then generate Client ID and Client Secrets for them? I have no problem executing manual work for the first 6 months, so I can log into Auth0 and create users manually, but need to plan on scaling.

Thanks,

Alejandro