I think connect-rpc[0] strikes a good balance between normal http apis, and gRPC. It allows protobuf as json. So you could think of it as an opinionated http api spec. A health check would be just a call to an url /something.v1.MyService/MyMethod -d { "input": "something }.
it works really well, and the tooling is pretty good, though it isn't that widely supported yet. Rust for one doesn't have an implementation. But I've been using it at work, and we basically haven't had any issues with it (go and typescript).
But the good thing is that it can interoperate with normal grpc servers, etc. But that of course locks it into using the protobuf wireformat, which is part of the trouble ;)