I think you misunderstood. We are referring to the navdata format. We are not able to update the RealityXP GTN750 as it used a proprietary Garmin navigation database, which is the same database as can be loaded into real world units and hence requires a full Garmin subscription.
As we cannot support this unit with current navdata, defaulting most flightsimmers to some outdated cycle, it also makes little sense to support flight plan loading as there would inevitably be data sync problems as our Charts apps use current data.
Very low demand (yes you are the first) including the complexities above makes this development hard to justify.
I hope that makes it a little clearer.
Regards,
Stephen