I haven't been able to figure out how to do this part at all (line 75 in the example I linked to): Decode the sequence and extract the single octet string that it contains. Verify that the string equals nonce.

I tried with asn1.js, but it seems that I need to specify the schema. I haven't been able to find any other library for JS/TS that does this. I'm really out of my depth here, and I can't believe Apple provides no resources that show how to do this on the server.

As I noted above, the problem is a recent version of the WebRTC package, which doesn't include the expected symbols. Using an earlier version solves the problem.

I also get the "undefined symbols" error when building with WebRTC M120 on an Intel Mac.

I'm building a native macOS app (not Mac Catalyst), and RTCMTLNSVideoView works up to M116. The WebRTC package supports native macOS builds. This is a bug with the WebRTC package.

I verified in the Push Notifications Console that the notification was "successfully delivered to the target device", however the didReceiveRemoteNotification delegate method is not triggered on macOS.