I don’t have one, but I know some people who do have them. It seems like the solar charging can’t keep up with the draw of regular smartwatch use plus the regular full cadence of sensor data acquisition. I think it mainly just effectively gives you a slightly longer battery life. Theoretically, in power saver mode or whatever with decreased sensor data acquisition, you might be able to get much longer.

Pulse oximetry in particular seems to be an energy hog. I don’t think any of the garmin solar smartwatches are really designed to not need to be charged.

In a pinch, you could probably keep one going for a very long time (and possibly indefinitely) in the power saving mode.