Mark Thomas has found some gps files on OpenRunner that cover the 2019 PBP route. Please read his note about those files before you use them.
For what they may be worth . . . .
Seeking RideWithGPS files for PBP for my own use, I traced the OpenRunner routes found on the PBP website and allowed RideWIthGPS to add cues. I cleaned those up a little. I added the controls. I split the route into Paris-Brest and Brest-Paris, because GPSs (and tired riders) can get confused when out and back are in the same file.
With no warranties of suitability, here they are - https://ridewithgps.com/routes/30717434
and
https://ridewithgps.com/routes/30717437
I would be happy to learn of any errors that you may find with these. Preferably before the event.
In France, you can almost certainly navigate by the reflective arrows that mark the course, so look up from the GPS and enjoy the ride.
Thanks,
Mark
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Some additional links (in French)
http://cyclo-long-cours.fr/2018/12/08/le-parcours-officiel-du-paris-brest-paris-2019/
http://cyclo-long-cours.fr/2018/12/09/paris-brest-paris-2019-etape-par-etape/