Multiple Stacks, API Gateways for different Clients

I am working on some macro-services on AWS that I want to clients (mobile, portal, thing, etc) to connect to. Because of the nature of the endpoints, we don’t want to expose all of the endpoints to all of the clients (there is nothing sensitive in them, we just want to keep documentation small and clean for the different clients). So I have the following services

\modules
       \product
       \user
       \thing

under product, I want some endpoints to point to
mobile-apigateway (subset)
portal-apigateway (subset)

under user, I want some endpoints to point to
mobile-apigateway (subset)
portal-apigateway (subset)

under thing, I want some endpoints to point to
mobile-apigateway (subset)
portal-apigateway (subset)
thing-apigateway (subset)

For code, I want to have all of the individual modules to be self-contained (i.e. a service), and be able to release only the subset of gateway endpoints for their perspective clients (to decouple all the modules from each other or some third master project). In the end, I just want to have 4 api gateways, instead of the 32 that I have right now and have human readable names. I have looked at Amplify, but it looks like I have to do up to 4 separate Serverless packages inside of the solution. I would really want instead of endpoints.yml something like

endpoints-mobile.yml
endpoints-thing.yml
endpoints-portal.yml

and each one be able to update just their section of the API gateway. Any help on this would be appreciated