@Cédric-Penalvert while watch faces are not available during an activity, I think you can still get what you want from your watch.
Navigation and waypoints are available during acticity recording. You can even have data fields with ETA distance to next waypoint, a graphical altitude profile etc.
With the new Suunto+ function “outdoor insights” you can keep track of the atmospheric pressure, temperature, sunrise/sunset times etc.
(provided you have the barometer version of the S9)