have the ability to create a CMP user that is a Service Account email (ie, without any active inbox associated to it)

I would like to have the ability to create a CMP user that is a Service Account email (ie, without any active inbox associated to it)They do not wish to associate an active inbox associated to it because this causes licenses costs:

We probably could associate an inbox to the email address but since this causes license costs (Microsoft Exchange etc.), we're having difficulties to justify the costs.
Especially since we have a pretty trivial use-case that's neither time-critical nor that important (using the invoices API to programmatically get invoice data without having to use personalised API tokens).

They ask the following question:

Is there anything on the roadmap for CMP to support the creation of non-personalised API tokens including custom permissions? (or for example something like ServiceAccounts in GCP -> users that do not have to be provided by the customer etc.)