I use a Stryd footpod and a Garmin chest strap on Zwift running, and a Garmin Edge and chest strap for cycling, is my Garmin Forerunner 965 now redundant?
If it's a high-end Edge, then it'll probably do everything that the 965 does. If it's an older Edge, the watch may have more features.
I don't know about Zwift's data collection and analysis, but if you are getting the data that you want, then I guess that you don't need a watch.