To be clear, the ring has NO "glucose tracking" features at all but is acting as a relay for the invasive glucose monitoring device that you wear that does the actual glucose tracking.
And really, this is done in the app that goes with the Oura - much like the app that the Dexcom device normally uses.
So really the use case here is "people who use a Dexcom device and don't want to carry a phone but are ok wearing a smart ring but then have to use a phone anyway, just later and are ok paying US$350 for that"?