User registration via mobile app - API Token best practices

Question to Okta gurus, I understand that user registration is not part of the Okta sign-in widget… yet… and Okta user registration API takes an API token as authorization token. My questions are…

Can we restrict the API token to be valid only for some APIs, like user registration only and cannot be used for other APIs?
Do we have any best practices on user registration flow?
Best practices on API token, etc.

Thanks for your help

When this user registration feature is launched, the registration endpoint will not require an API token (very similar to how the AuthN API works). Currently, API Tokens are not restricted, we do have a feature on our roadmap to support OAuth 2.0 for the Okta APIs that should resolve this. The timing for this enhancement is unknown.

What are the timings for user registration feature? Is that also unknown?

Do you know when the API will allow OAuth 2.0 and will it support the client credential flow?

I am actually in need of this the user registration flow. I have looked at the API documentation but can only find one way to do this using an app token. The challenge here is the app token expires after about a month, at least from what I saw with my developer account. My use case is to register users from a mobile hybrid app and I am not sure I can afford to do a new update just to change the token.

Another work around would be to let users submit to my backend system and then make a call to Okta from there but that clearly can only be done if there is no better way. Is there a better approach to this?