Apple Watch predict Glucose?

Hey all! I'm trying to learn how to do machine learning, and I thought a cool project idea would be predicting glucose. Has anyone ever tried using an Apple Watch/Fitbit/Garmin to *detect or predict* glucose? Like as a rough early warning using HR/HRV/temp/activity, etc. I know CGMs are the gold standard and this wouldn’t replace one, but I’m just curious if anyone’s seen apps/studies/DIY attempts that actually work (or totally don’t). Any links or “here’s why this is a bad idea” welcome. Thanks!