Strava routes
Upload the GPX in Strava Route Builder on the web, save it to My Routes, and avoid creating an activity by mistake.
Garmin watches
Forerunner, Fenix, Epix, Venu, Vivoactive. Import as a Course in Garmin Connect, then send to watch.
Apple Watch
Use Komoot, Strava, WorkoutDoors, or another GPX navigation app because Apple Workout does not import GPX routes directly.
COROS
PACE, APEX, VERTIX. Open the GPX with COROS, save it, sync it to the watch, then start Navigation.
Suunto
Vertical, Race, 9 Peak, 5 Peak. Import GPX in Suunto app Maps, save to your library, and sync to watch.
Polar
Vantage, Grit, Pacer. Import GPX or TCX to Polar Flow Favorites and sync it to a compatible watch.
Bike computers
Garmin Edge, Wahoo ELEMNT, Hammerhead Karoo, Sigma ROX. Best file format and where to start navigation.
Before you start: export GPX from Trasely and save it to Files if your device app does not appear directly in the iOS share sheet.