One time I had issue with getting mail notification on my watch, I have to go to the watch app on iphone > Mail > Accounts and login to my email accounts. Some of them shows "Sign in required" for some reason. After that the mail notification works perfectly on my watch.
Not sure if it's the same as your issue though.
More info about the double tap feature on series 9: https://support.apple.com/guide/watch/use-double-tap-to-perform-common-actions-apdabb7b275c/watchos
I want to like this watch face, but it's just too much information for me. At a glance I won't be able to tell what the things are and it'll take me more time to interpret the information. Maybe it'll be better if I give it enough time to get used to the layout.
Series 4 have been around for a while and if it's still on the original battery, the battery health is probably the issue. You may want to check the battery health of your series 4 and decide if you want to get a new battery or a newer watch.
I don't work for Apple, so can't say if it's just Apple gatekeeping features for higher-end watches or there is really a technical reason. However, I think you overthink too much about the keyboard feature. I'm using an S7 and I would only use the keyboard to do really short replies and will take out my phone for anything longer than a few words.
Love the milanese loop.
They will give you a refurb unit.
Already talked about this: https://www.reddit.com/r/AppleWatch/comments/17w9yaz/watchos_102_beta_reintroduces_option_to_change/
Same here, quick actions is hit or miss for my series 7. I haven't tried ultra 2 or series 9 though, so can't comment if double tap is more accurate.
In addition to the red ring that other people said in comment section, a cellular watch should say LTE in the caseback. Maybe get a picture of the caseback to confirm as well?
Time to change the passcode to "2222" and continue to use it for another 10 years! Just kidding.
Looks like it had a good run already, time for an upgrade!
When there is a notification, I can use my apple watch to separate out notifications that I need to immediately respond (e.g. important message/call from work or family) vs ones I can take care of later without taking out my phone. Before having the apple watch, I have to take out my phone every time when there is a notification.
I also use Apple pay with the watch all the time without taking out my phone.
Both of these use cases works with non-cellular version as well. Of course you'll need your phone nearby or have wifi so you can receive messages, but it doesn't require you to have a cellular watch or have the cellular plan on the watch.