The well-known leakster, Evan Blass, just shared that Gear smartwatches running Wear OS were spotted on the wrists of Samsung employees.
All Samsung Gear smartwatches over the past three years run Tizen OS, which is rather functional and offers some nice features that Wear OS lacks.
However, Tizen OS' downside is the number of available apps, where Wear OS has a clear advantage over it. Some may argue, of course, that you don't need as many applications on a smartwatch, but that's beyond the point here.
We are yet to find out if Tizen will remain and be limited to some devices or if Wear OS will replace it completely.