OTLP specifies payload schema in protobuf, but it supports gRPC and HTTP (both 1.1 and 2) both with protobuf and JSON payloads. In fact, the default for exporters defined by the spec is not gRPC but rather HTTP/protobuf opentelemetry.io/docs/specs/o...

OpenTelemetry Protocol Exporter

Status: Stable This document specifies the configuration options available to the OpenTelemetry Protocol (OTLP) Exporter as well as the retry behavior. Configuration Options The following configuratio...