This app does its thing without needing to connect anywhere. All the antenna data is bundled with the app, so the app doesn't connect to the Internet at all for its main operation.
However, I use AdMob to display ads. This is a service by Google that sends some information about you to better target those ads (in particular the Android Advertising id wil be sent).
In some cases you may have been presented with the option of receiving non personalized ads (this is to comply with GDPR). In that case the paragraph above doesn't apply to you.
I also use Crashlytics and Firebase Analytics to send non-personal data about usage patterns, crashes, etc. This is vital for me to improve the app.