Garmin Connect for push-ups workout

You mean that you would put the phone under your body while doing push-ups?

The watch actually counts push-up surprisingly well. At least if it knows before-hand what is going to happen.

My Forerunner 955 doesn't accurately track push-ups.Even when I created a workout for push-ups.

The watch is looking for specific movement patterns. Maybe try doing the push-ups differently.