Tirado, Carlos Thanks for posting your question in Microsoft Q&A. Currently, only inbound connections to API Management are supported. The outbound connections are not supported (like here connections to Azure Functions in this case) and check out the same in doc https://learn.microsoft.com/en-us/azure/api-management/private-endpoint. So, you cannot configure outbound connectivity from APIM to Functions via Private endpoint (similar discussion).
However, we have introduced public preview of new pricing tiers which supports private networking to and from your API Management service instance (to service like Functions) and check out the update: https://azure.microsoft.com/en-us/updates/announcing-public-preview-of-azure-api-management-pricing-tiers-basic-v2-and-standard-v2/. For any feedback requests, feel free to submit it directly to our product team via https://aka.ms/apimwish.
I hope this helps and let us know if any questions.