TWA-Web App postMessage Integration

I'm looking for a skilled developer to implement postMessage integration for a Trusted Web Activity (TWA) and a Web App. The integration should support bidirectional communication.
Preferably following official documentation at: https://developer.chrome.com/docs/android/post-message-twa.

Requirements:
- Sending and receiving system-generated data
- Handling acknowledgements and status updates

I mainly want to delay the notification permission popup until the user gets registered. Idea is to initiate the notification popup only after receiving confirmation from web/JS that the user got registered.

Ideal Skills:
- Experience with TWAs and postMessage API
- Strong knowledge of web app development
- Proficiency in JavaScript and handling cross-origin communication
- Proficiency in Java


Please provide examples of similar work done.