Windows App SDK push notification error

Question

I’m working on a WinUI 3 application built with the Windows App SDK, and I’d like to integrate WNS push notifications.

To obtain the channel URI, I’m using the following code:

var result = await PushNotificationManager.Default.CreateChannelAsync(RemoteId);

I've also added the COM server configuration in the app manifest:

<com:Extension Category="windows.comServer">

<com:ComServer>

<com:ExeServer Executable="myapp\myapp.exe" DisplayName="myapp" Arguments="----WindowsAppRuntimePushServer:">

<com:Class Id="app_id" DisplayName="myapp" />

</com:ExeServer>

</com:ComServer>

</com:Extension>

The channel URI is successfully generated, but when I attempt to send a push notification, I receive a 403 (Forbidden) error.

For the RemoteId, I’ve tried both the Azure App Registration ID and the Object ID, but neither worked.

According to Microsoft's documentation, I need to map my app’s Package Family Name (PFN) to its Azure AppId by emailing Win_App_SDK_Push@microsoft.com. I sent the request over a month ago, but I haven’t received any response.

Is there any alternative way to proceed, or someone I can contact to get support on this issue?