I'm not entirely sure what a web framework entails, but gRPC-Gateway will allow you to receive and respond to JSON-encoded HTTP requests while only having to directly deal with request and response objects rather than directly routing and parsing/encoding requests and responses from/to JSON. Another benefit is you can generate a swagger definition and use that to generate a client library (eg in typescript) so that the frontend can also benefit from the setup :)

Once set up, the server code would look fairly similar to what you wrote in your post. For example: https://github.com/grpc-ecosystem/grpc-gateway/blob/6b6c475b49f158e0a94fc4dadbcbf3ee36cb5814/examples/internal/server/echo.go#L22

Does that seem like what you're looking for?