The reason why Google has decided to review the Wear OS application is that they want to be a 100%sure that it is of the best possible quality. In order to make sure that customers succeed with useful apps for Wear OS all the apps will be evaluated as for the standard quality. Even though the review wasn’t mandatory before, starting with October, it will become such.
All the apps are bound to be reviewed. Otherwise, they may be deleted from the Play Store, and the deadline is March 4th, 2019. As for the requirements of the review, it is a must that the app fits various types of screen, and there is a corresponding screenshot available in Play Store.
The reason why it is so vital that Wear OS fits all the screen lies in the versatility of Android devices available. What is more, the screens are also round and square, and that should be taken into consideration as well.
Those applications that are still in the development stage can skip the review phase so that it does not interfere with the development process before the launch itself.
In case you are among those who have Wear OS on your Play Store you better review it now. Such actions will surely help Google reviewers to deal with the task easily since the amount of work will surely be tremendous.