Which GLP-1 tracker has an Apple Watch app?

Phaze and Shotsy both ship a real Apple Watch app, with different focus. Shotsy on the watch leans on injection logging and dose reminders, in line with its iPhone strengths. Phaze on the watch covers dose logging, weight entry, water, fasting timer, and complications you can put on a watch face for one-tap dose, weight, or water. Phaze on watchOS works without your iPhone for log-only tasks once it is set up. Pep, Mingo, Regimen, and Glapp do not ship a full watch app at the time of writing, though some have notification mirroring. The Apple Watch GLP-1 tracker guide on this site covers what the Phaze watch app does in more detail.