I upgraded inadvertently 2 days ago to Android Pie with a pure Android phone (Moto G4 with Google Fi), and lost all Dexcom Follow alarms for good. No solution in sight until Dexcom qualifies a new version of the app. Since they need to get it approved it may take months.
So now I have to switch to an iPhone to monitor my kid at night. I am really unhappy. Don’t do this.