I’ve got one of the older Apple watches and use hole19 lite version which allows you to input scores on the watch itself, shows front, middle and back yardages. I did have the premium version but never used the extra features so just went with lite. Free doesn’t let you input scores on your watch.
Never had an issue with battery life on the watch or phone, even when I’ve played a round both last until I go to bed when I normally charge them anyway.
Signal/gps has generally been fine, occasionally if I’m out in the sticks it can take a while to find 4g, or you can connect to the WiFi at the course and download it via that. Or download it at home before leaving.
Newer Apple watches come with inbuilt 4g I believe, meaning you wouldn’t need to have your phone nearby.