I think GraphQL is absolutely suitable for being exposed as a public API. Given a schema, it's arguably simpler to write clients than with REST, where every API

I think GraphQL is absolutely suitable for being exposed as a public API. Given a schema, it's arguably simpler to write clients than with REST, where every API is completely ad-hoc with respect to how you pass parameters, paginate, select which fields (including nested data) you want, etc. I think the more interesting question is whether GraphQL is a suitable inter-application API foundation. In many ways it aligns better with application requirements than gRPC. gRPC is even farther away from REST, with limited abilities to do field selection and no inherent support for nesting. And gRPC needs special help to work in browsers. What gRPC has is a compact serialization format and a toolchain that encourages using Protobuf structs for your own internals. When implementing an app, it certainly seems redundant to offer both GraphQL and gRPC.