Hi PaulFromThe90s,
Thanks for contacting Apple Support Communities!
We understand that you'd like to include a route in the Workout app on your Apple Watch.
The Apple Watch does allow for you to create a custom workout but, it doesn't include a feature to import or create a route for your workout. You can learn more about the features of the Workout app here: Use the Workout app on your Apple Watch - Apple Support
"Customize a workout
You can add structured intervals to most workouts.
- On your Apple Watch, open the Workout app.
- Tap the More button
next to the workout that you want to do. - Scroll down and tap Create Workout, then tap Custom.
- Tap Warmup to set a Goal Type or Skip.
- Tap Add, then tap Work or Recovery and select a Goal Type.
- Tap Cooldown to set a Goal Type or Skip.
- Enter the Custom Title of your workout.

8. Tap Create Workout.
Your custom workout appears as an available goal option for the selected workout."
Take care!