You mean nothing?
Again if you buy into that frankly absurd narrative you have to believe that a variety of third party studios developed games for a 4K Switch... Only for all of these projects to be cancelled, with no consequences to Nintendo's relationships with 3rd parties of no stories leaking to the public outside of the pathetic attempts at damage control from "insiders".
This isn't even mentioning the fact there's zero trace of a Pro system in the Nvidia hacked data that revealed the existence of the Switch 2 SoC, years ago.
the plans for this pro model could have changed early on during development, or early enough for it never having an SDK going to devs.
the fact that they switched memory types to one that has a higher bandwidth, and the potential for more memory on a single module while retaining the same package size, is one big indicator for this imo.
if you replaced it's 2x2GB for a 2x4GB configuration, and clocked the X1+ chip to the max clock speed in docked, and maybe a 1.5x~2x increase in handheld mode, you would have roughly the same battery life as the launch Switch, while massively boosting game performance, especially in Docked mode.
it really wouldn't take much to turn the OLED into a Pro. 2 memory module changes and a software side clock speed increase, that's literally it.
the ease at which this systen could be changed into a pro model could also be the reason Nintendo could change course without much of a hassle, and without there ever being a third party working on a Pro patch for games.