Airframes for Default Aircraft in X-Plane

I am a past customer who has been doing VFR training. I am now looking at getting into IFR and evaluating Simbrief and Navigraph. Both are very impressive but I would think that all of the default aircraft provided by X-Plane, P3D and MSFS would be on the airframes list. I do see the 3 X-Plane airliners but not the GA aircraft. Also missing are the Cessna 182 and 206. I am using X-Plane. The Van’s RV10 is now a default in X-Plane 12. The SAIA Marchetti by the team of Javier Rollon of X-Plane fame and Simcoders would be nice too. Maybe Navigraph and/or Simbrief should or could create a portal for plane developers to add their planes to the list. Thank you.