Galaxy S9 / S10
Start Device care from phone settings. > Tap Battery. > Tap the 3-dot menu > Settings > Disable all toggles (except Notifications). > Tap Sleeping apps. > Exclude Pedometer using the trashcan icon.
Galaxy S8
Open Settings > Device maintenance > Battery >Unmonitored apps. When inside the unmonitored apps menu, tap the 3-dot menu. Now you can exclude Pedometer from the App power monitor.
On other Samsung phones, the path may look like this:
Phone settings > Applications > select three dot menu (top right corner) > Special Access > Optimize Battery usage > Find Pedometer app on the list and make sure that it is not selected.