Thanks for reaching out.
If you want to make your push notifications more persistent, I’d recommend setting up multiple push notifications to get your attention. You can do this in PagerDuty under My Profile -> Notification Rules.
You can also add custom ringtones and notification sounds to your system ringtones on your Android. To do this, go to the Sound settings on your phone and then Ringtones (or push notifications). You should see an Add button which should allow you to add in your ringtones and sounds.
Another option is to use an app such as Rings Extended which overrides system settings.
Once you have completed one of the two options above, open the PagerDuty app and go into the settings. Select System Sounds, and you should now see your custom ringtones.
I hope this helps. Let me know if you have any further questions about this.