I’ve looked into your issue and found that your app is not compatible with the Galaxy S10 to a conflict in your app’s manifest with the following feature: android.hardware.type.watch .
WFS sets that in the manifest by default. It is mentioned in this seller portal note
: The following information should be included in the manifest file for app registration for Wear OS. <uses-feature android:name="android.hardware.type.watch" />
(When utilizing 'Android Studio, Watch Face Studio, or Galaxy Watch Studio Converter to create content, the information is included as default. )
I think you just didn’t have your Watch4 as the paired watch in your phone. That would give that error in the Play Store.
I think there is a communication issue between Galaxy Wearable and Google Play on Fold 3. As I mentioned in this post that I can’t find any watch faces made from WFS on Fold 3 and there are no watch and watch face subcategories in the search result. Same search on S10 shows many watch faces made with WFS.
I don’t know if this is an unique problem on my Fold 3 or all Fold 3 users are experiencing the same issue.