I have Strava (on iPhone and watch), which is strictly speaking a running/cycling app. Last night I went for a 20 minute walk up some steep hills (HR 110 - 130), I told Strava to record my "run" in the Glances screen, it recorded the route and my HR, Activity recognised it as 20 mins exercise as part of my daily 30, and Lifesum (my food intake monitor) also recognised it as exercise. No need to enter it in Activity. After all, your walking speed could be my running speed, so these apps don't differentiate between activities as long as you're moving.