Greengrass Lambda with Compressed Binary Payload

I'm trying to configure a Greengrass Lambda to accept a binary encoding with the goal of sending a compressed JSON payload. My Lambda configuration looks something like:

  "componentLambdaParameters": {
    "inputPayloadEncodingType": "binary",
    "eventSources": [
      {
        "topic": "my/topic",
        "type": "IOT_CORE"
      }
    ],
    "linuxProcessParams": {
      "isolationMode": "NoContainer"
    },
    "pinned": false
  }

I'm using Python/Boto3 to send the messages, and the topic publish looks something like:

client = boto3.client("iot-data")
payload = gzip.compress(json.dumps({"large": "message"}).encode())
client.publish(topic="my/topic", qos=1, retain=True, payload=payload)

I get the following error from the Greengrass Lambda:

lambda_runtime.py:183,Cannot parse given invoke payload as JSON: b'my contents'

I can send the same message without compressing it (e.g. payload = json.dumps({"large": "message"}).encode()), and the Lambda succeeds. That suggests to me that "inputPayloadEncodingType": "binary" setting only works if the payload is encoded JSON, but that seems to defeat the purpose of using the binary payload option to send something other than JSON.

I'm using the Python 3.8 Lambda runtime with following component versions:

  "aws.greengrass.LambdaLauncher": {
    "componentVersion": "2.0.10"
  },
  "aws.greengrass.LambdaManager": {
    "componentVersion": "2.2.2"
  },
  "aws.greengrass.LambdaRuntimes": {
    "componentVersion": "2.0.8"
  },
  "aws.greengrass.Nucleus": {
    "componentVersion": "2.5.5",
  },

Is there something I might be doing wrong here or any other guidance on accepting a compressed payload? Thanks!