To Send a push in production to only a specific device please go over the following steps.
Make sure you have the Store App and that you are registered for push.
Open the App > Side Menu > Settings > Contact us > Report a problem.
Most Applicaster apps will have this and it will prompt an Email composer with the following details for example.
Copy the UUID number and open ais.applicaster.com
Navigate to the desired App and paste the UUID in the search device box.
You will see the device details, click on the Push token and copy the string -
Inside the message composer, choose "Target Specific Users" and enter the push token and select the device.
You can now send a push on the production app only to the specific device.