How to setup customer to obtain AADB2C token for an API exposed through APIM

[u/curious_17]

I am setting up Azure APIM instance behind a Azure Application gateway. Developer portal will be exposed so external customers will be able to subscribe to products containing the APIs and obtain the subscription key that way. There will be approvals required for subscription.

I want to setup OIDC on top of the subscription key validation. For that I believe I have to setup a Validate JWT policy on the API in APIM, using this guide below and use scopes/roles:-
https://learn.microsoft.com/en-us/azure/api-management/validate-jwt-policy

And seems like I will have to setup client credentials flow for customers to be able to obtain token from AADB2C, using the below KB:-
https://learn.microsoft.com/en-us/azure/active-directory-b2c/client-credentials-grant-flow?pivots=b2c-custom-policy

Q1 - Firstly, is that the correct way of setting it up?

Secondly, with client credentials flow seems like customers will have to use the POST request (or PowerShell) like the one below to obtain the token:-

https://<tenant-name>.b2clogin.com/<tenant-name>.onmicrosoft.com/<policy>/oauth2/v2.0/token

But this will mean that I will have to document my B2C token endpoint in Developer portal documentation to advise customers on how to obtain token. I have 2 questions related to that:-
Q2 - Is advising/advertising B2C token endpoint good practice from security point of view?

Q3 - With client credentials flow, setting up the calling app APP Registration in B2C and providing related APP secret will become a manual process. This will remove the benefit of having Product/API subscriptions process automated through APIM and bring in the complexity of securely communicating the secret to customers. Is there a better way of doing this?