I was encountering a bug when adding an unread widget to the home screen when using fdroid’s (then my own build of) com.benny.openlauncher. I noticed a permission denied in logcat near APPWIDGET_CONFIGURE intent. That led me to try rebuilding k9app with toggling app/k9mail/src/main/AndroidManifest.xml line 259 from android:exported=“false” to true. Which seems to have fixed the issue and crash in openlauncher (which is at least a bug in that it should report a permission problem and failure to add widget instead of crashing). Still, being fairly green with 'roid stuff, I wonder if this is the right fix, (vs something else in openlauncher perhaps). Or, if it is, hopefully it can make it into future k9 releases.
It works fine with the default launcher on my test devices.
The launcher should probably use AppWidgetHost.startAppWidgetConfigureActivityForResult() not trying to start the configuration Activity itself.