Unfortunately, the approval of the companion app for WearOS on Google Play is proving to be a nightmare (first they approve it and then non-existent problems are detected with each mobile/WearOS update) which are also causing serious delays on the mobile and TV versions.
For these reasons, the WearOS apk will no longer be available on Google Play, it is instead possible to download it here WearOS companion apk
To install it you can search for guides on Google by typing "WearOS apk sideload"