How can I forward Protobuf message in rule chain?

Question

I'm sending Protobuf messages from my IoT device to ThingsBoard via MQTT. So far, that works and I can see the telemetry data in the ThingsBoard UI.

Now, I would like to forward the Protobuf message to an external server via the rule chain, but it seems like ThingsBoard converts the Protobuf message to JSON. Can I forward the Protobuf messages as they are?

This is my current rule chain:

Edit: Additional Info

I can read and write the messages as JavaScript objects before they reach the REST node. In fact, I can view the messages in JSON format in the first debuggable node, i.e. the "Device Profile" node:

Since Protobuf is configured in the device profile's transport configuration, I assume the conversion happens before the rule chain and that you cannot forward the Protobuf message. Can someone confirm this?