support.garmin.com
The single best thing you can do is link GP on your device to a flight simulator such as MSFS or X-Plane. Then just have the simulator do an autopilot flight while you fool around with GP as it reacts exactly as it would for a regular flight.
Not sure if there has been a change since you wrote this, but for fun just I created a cross-country including adding enroute points and an arrival procedure without ever leaving the map page in GP. The little magneta/dashed-line symbol on the radial menu puts you into graphical FPL editing mode which lets you tap to add waypoints, drag to edit the flight path as needed, and add altitude constraints, off-track offsets, arrivals, and approaches. Not sure if you were referencing something else, but it appears that using the map page or the flight plan page are both excellent options depending on whether you want to do it graphically or just enter a list of previously-determined waypoints by identifier.
Have you used both? If you have, you obviously don't see the degree of difference I do. Which is a good thing.
My FF experience is limited to the 30-day trail, so my knowledge is pretty incomplete. My impression during that trial was that it was powerful but that the UI really didn't work for me in the way that GP did. Certainly the desktop planning app was great (and something Garmin is only now really working on replicating).
Yes, ultimately most of it can. I was really referring to the focus of the apps and that differences reflected where they started from. That's why one's UI worked better for you than the other.
