Condal definitely said that GRRM told him that Aegon was a dreamer and that motivated his conquest of Westeros. I def think there is going to be more reveals related to The Prince that was Promised in the Dunk and Egg novels with Aegon V and or in Winds/Spring with Rhaegar.Ya'll thinking about it too much
The heir prophecy story is simply a show only thing and makes no sense when you consider targaryen succession since Aegon I
I mean the showrunners can't even tell where the dragon eggs come from and are making mistakes even now with the lore
Tv show is about entertainment first and consistency second
Or there would be if they were ever written I think GRRM is now giving these little tidbits to showrunners working on the shows.