It works with Garmin's own Connect app. If you use the watch for tracking your rides and also wear it off-the-bike (particularly while sleeping), you'll get a tremendous amount of data: training readiness (with submetrics to explain and interpret it), sleep data, body battery, resting HR, etc. I bought the Fenix 7 last year, and it has improved my training tremendously. The sleep data alone led me to cut back my alcohol intake a lot, which has helped my sleep and hence hence training readiness.

Now, if you just want some more simple fitness data (HR, step counting, RWGPS ride tracking, etc), an AW is probably fine. And if you value the smartwatch features, the AW is superior to a Garmin. (I do sometimes miss the AW smart features. If you also use and iPhone, it's pretty great.)

Note that the 955 has a MIP (transreflective) display, which is great in sunlight but not as colorful and vivid as an LED display like the AW. The Garmin Forerunner 965 will give the same feature set with a more modern-looking LED display (with battery life that is still way better than an AW, too.)