Mapping distributed data across microservices, without the API spam or replication?

Hi everyone,
I recently ran into a problem with our microservices architecture: the data is spread across multiple services.
For example, PatientId lives in Service A, but the actual patient info belongs to Service B. That's just a small example. I've got a ton of stuff to map, like master data, patient info, medicine info, and so on.
I'd rather not write a bunch of API calls by hand or replicate data everywhere, so I've been working on a small library for it called FxMap. You declare what you need once with a fluent API, and it fetches and fills in the remote data over gRPC, RabbitMQ, Kafka, etc. It's still pretty young, so honest feedback is very welcome.
Has anyone else dealt with this? Curious how you handled it, or if you'd do it differently.