Steves suggestion above is valid, and the TickrX has loads of features that wyou wouldn’t imagine that makes it a very capable device, but top see live metrics, you need to have access to your phone screen, which I, like Steve do not find functional, so we are back to watches!
I’ve used various Garmin and Suunto over the years, and I know there are people who will read this and baulk, but I love the Apple Watch, and believe is as good as any for multi-sport activities, and it’s probably not taken as seriously as it should be. Ive been using it for serious training for a few years now, and with a few initial tweaks, it dovetails into my training perfectly, seamlessly and easily, more so than any other watch I’ve used.
For the doubters, I would highly recommend reading TheAppleWatchTriathalete (https://theapplewatchtriathlete.com) where the author has successfully used an Apple Watch in a couple of Ironman events, and used it exclusively for his training for quite a few years now. He has tested many apps and third party additions, and his findings are very balanced. He has even written an article for Training Peaks about its use in IronMan events, so with that pedigree, I think it can manage a bit of hill running!
My set up is simple in that I use the native Apple Activity App, as I think its metrics are great, it has all the features of a ‘specific’ sports watch (rolling pace, av Pace, pace alerts, splits, transition between activities etc), and I find the screen layout is easy to read
I use Training Peaks as my ‘Hub’ although im also on Strava for the ‘coomunity/social’ stuff.
My main ‘catalyst app’ is a great app called Healthfit (https://apps.apple.com/us/app/healthfit/id1202650514) which automagically syncs with the native Health App (which has picked up the workout from the Activity App), and then onward syncs it to Training Peaks and Strava in my case.
Healthfit also syncs with Strava, Runalyze, Smashrun, Map my Run and loads of cycling apps, as well as Dropbox or iCloud for hard data storage, AND it also picks up other health metrics from other apps I use (MyFitnessPal, Waterminder and Sleep++) which all get added into my Training Peaks Account daily without me doing anything.
All this might sound complicated, but when its all set up (took minutes), it all just works, and I just do my training and everything is there on Training Peaks.
Its also nice to activate the calendar feature in TP, and so in the morning I see on my watch face what my workout is for the day, based on my ATP.
I hope this helps