Is non-invasive glucose monitoring technically feasible in a smartwatch?

Rockley Photonics has done a lot of work to make that happen, maybe enough that the answer is “Yes”: https://rockleyphotonics.com/wp-content/uploads/2021/03/Rock...

https://rockleyphotonics.com/wp-content/uploads/2021/07/Rock...

Or summaries: https://www.macrumors.com/2021/07/14/apple-supplier-unveils-... , https://www.macrumors.com/2021/05/03/apple-watch-blood-press...

Whether it’s in the Apple Watch 8, 9, or a special-purpose device is anyone’s guess, as is the accuracy. It seems like they’re pretty far along, though.

Yes

https://www.pkvitality.com/ktrack-glucose/