Given apphosting supports multiple configured backends, it would greatly improve the emulator's utility to provide a mechanism to emulate all of them locally. With this feature in place firebase can support local emulation of apphosting and cloud run backends configured using hosting rewrite rules when deployed, which is a big win for supporting any number of microservices behind a single domain for integration testing and local dev. We'll still be responsible for implementing a local service discovery mechanism, but we'll have the convenience of just the emulator for spawning all our app processes.

From the outside the feature looks like it could be easily implemented with a map on the backend array, so if it's truly small in story points I encourage the product team to prioritize it.