Passing flatbuffers to postman?

I need to test my API with messages packed in Google Flatbuffers. I want to run these tests both locally and on CircleCI.

Can I set this up with postman? It seems that we cannot import arbitrary external modules into the Postman scripting sandbox.

Specifically I would need:

import * as flatbuffers from 'flatbuffers';
import { MyFlatbuffersProtocol } from './my_protocol_generated_by_flatbuffers';

// Create flatbuffers message.
// Send to API endpoints (both websocket and HTTP). 

I’ve already tried:
Reading the documentation and searching the community posts.

Any postman staff here to respond to this? Unfortunately it looks like I will not be able to use postman if I can’t integrate this into the pre-request scripts. It would be awesome if postman could allow arbitrary client code instead of the sandbox environment. Makes it impossible to test non-trivial in-house message payloads that we construct with our internal libraries etc.