This can be done in the event's admin.
1) In the admin portal click on the client from the client list.
2) Go to Solutions and click on the solution the event is from.
3) On the Events tab click on the event from the list. You can also search for the event name or ID.
4) On the Participants tab click on the participant from the list. You can also search for the participants name.
5) Go to Devices tab and click on the device/devices.
6) Under Push Log check the push notifications sent.