I feel the same way. I can’t load the app either on my Galaxy Watch 4 or my Fossil Gen5 because the PlayStore tells me the watches are incompatible. I bought SmartLock Pro 3.0 yesterday specifically because of the smartwatch support.
As far as I can tell at this point, it is clearly a case of fraudulent misrepresentation. I quote the manufacturer:
“Use Nuki with your smartwatch
The Nuki app is also available for the Apple Watch, Android smartwatches (Wear OS) like the Garmin Watch, the Galaxy Watch (Tizen OS) and the Huawei Watch (HarmonyOS).”
It would be important for me to know if support for these watch models is generally discontinued or if this is a short-term temporary problem.
This would greatly influence the decision of a refund.