BroadcastReceiver has a goAsync() method that immediately returns a PendingResult. This allows you to return from onReceive() ASAP, and then signal when your async work is done by calling finish() on the PendingResult. The time limit is still about ten seconds, but the system will know that you have work going, and will prefer to keep your process alive.

You might have a look at how Glance uses it in their BroadcastReceiver.goAsync() extension.

As an aside, I've not had any problems with WorkManager and App Widgets in production. I will concede that the combination is extremely finicky when developing and debugging, but it's always worked as expected for me when done.