No for some reason Apple allow you to delete it but it is not in the App Store (I reported that to them as illogical)
You will need to unpair and re-pair, though a forced restart may bring it back.
Start by force restarting the Watch and paired iPhone at the same time:-
Force restart the Watch
i.e. press and hold both the side button and Digital Crown for at least 10 seconds, then release both buttons when you see the Apple logo. Then while Watch is restarting,
Force Restart the paired iphone Force restart iPhone – Apple Support (UK)
You may also want to update to OS9.5 and iOS16.5 if you have not already
Update your iPhone or iPad - Apple Support and
Update your Apple Watch - Apple Support
If it is still missing...
Unpair and set up again
Unpair and erase your Apple Watch – Apple Support (UK)
and then set up again - takes about 20 minutes
Set up your Apple Watch – Apple Support (UK)
If necessary unpair and setup without restoring the backup