The UTM Tracking add-on adds UTM campaign tracking parameters to the Start Page URL (start_url) in the manifest. This will help you identify visitors coming to your website from your PWA.
The add-on is shipped with SuperPWA WordPress plugin and can be activated from the Add-Ons page in SuperPWA > Add-Ons.
After activation, go to SuperPWA > UTM Tracking to change the default settings as needed.
Only the Campaign Source is mandatory. The rest of the fields are optional and you can see them as it suits your tracking needs.
Once activated, your Start Page URL (start_url in manifest) will have the UTM parameters appended to it. You will start to see these in the source/medium report in your analytics software.