Before the release of Galaxy Watch 3 the seller portal reviewed content for compatibility with GW3. The current compatible device lists should include Galaxy Watch 3 for most Watch Face and Watch Apps.
However it is recommended that if you have released new or updated content in the past month that you verify that it is available for Galaxy Watch 3.
The number of available devices is around 1733 - 1738 at this time and if you exclude Gear S2 devices the number should be 1335 and larger. If you are seeing a number of devices less than 1335 you should update your devices in the seller portal.
Sign in to the seller portal
Select your device
Click on Binary and there is a red number for selected devices, see how many devices you have listed.
If it isn’t 1482 or greater you need to update.
Click on the red number for “Selected Device(s)”
A dialog window with a large list of hardware combinations shows up. Don’t get confused.
In the search field at the top right enter “Gear S2” - no need to press Enter.
The displayed list now only contains hardware combinations including the S2 watch.
Now check the check box “Select all”.
Despite the message still reads the same total, you have in fact deselected all S2 combinations, about 358 device combinations
Click the “Save” button at the bottom.
1375 or more devices should now be available
Your previous binary will still be available while the new versions are added
Samsung Developer Team