Unable to answer "What’s the surface firmness of this track?" – Route de la Trémouille (Track / Land-Access Road) – https://osm.org/way/1297646552 via StreetComplete 57.1:

Pas de route ici

Attached photo(s):
https://westnordost.de/p/221344.jpg
https://westnordost.de/p/221345.jpg