Yes you need to look in French and/or Spanish. It’s logical to expect there to be way more information available in the native language of the country than in English.
My French is pretty dire but I found this site when looking for routes in the Haute Savoire, there are 5000+ GPX files online. I suppose there are routes for Pyrenees too. You can see maps but to get GPS files you need to register (I failed to manage that but that’s due to me). there is search function by region (dept), mountain range (masif) etc
It’s not so hard to follow …
Itinéraires VTT avec traces GPS – Mountain Bike routes with GPS tracks
utagawavtt
I randomly picked this route near Pau link
A few words to help searches …
VTT (velo toute terrain – mountain bike)
Randonee – a tour
masif – mountain range
dept (department) an area/region