You can still track your walks without the Apple Watch in tow, but iOS 16 will also let you track other activities using the Fitness app and the iPhone’s built-in motion sensors. The iPhone can track your steps, distance walked, and any workouts you do within compatible third-party apps, and they’re all tallied toward your daily fitness goals.
The Android ecosystem hasn’t had the best track record with smartwatches. The best thing we have right now is Samsung’s Galaxy Watch 4. To its credit, Samsung has enabled third-party apps like Strava and Google Fit to allow you to track activity, along with its proprietary Samsung Health. You don’t need the watch to do all that, though, or to aggregate fitness data within Google Fit.