I keep seeing glucose watches everywhere — are they real?

I've been seeing more watches and rings online that claim they can measure blood glucose without finger pricks or sensors.

The idea sounds amazing, especially because the ongoing cost of strips and CGM sensors can become expensive over time. But I'm not sure how accurate these devices actually are or whether they are just showing estimates.

Has anyone here tried one of these non-invasive glucose watches or rings? Are they useful for tracking trends, or should they not be trusted for diabetes management?

I'm also curious about the long-term cost compared with regular glucometers and CGMs.