API Gateway vs Direct Service Exposure

Your design has twelve microservices. A mobile app opens its home screen, and that screen needs data from five of them.

Does the app call the five services directly? Or does it make one call to a single entry point that calls them on its behalf?

This is the choice between direct service exposure and an API gateway. It is really a question about where shared work lives. The work does not disappear either way. Either every client and every service carries it, or one component you must operate carries it.

Direct Service Exposure

Each service publishes its own public endpoint