I see your point but I have to completely disagree on the allure of such device.
The market is FULL to the brim with devices that shares 98% of the industry library, a portable PS5 won't entice Playstation fanbase (majority of owners) who would rather invest in a future proof PS6, nor it will allure anyone from PC who somewho can manage to play said games in various configs.
So Im sticking to my point, either make it play PS6 games or don't do it at all.
if the handheld is successful, Sony would also be motivated to make PS5 ports of most of their PS6 games.
while also having the option to make games for PS6, that simply wouldn't be possible if they had to take the handheld into account.
it's simply unrealistic that they could make a handheld at a decent price and with decent battery life, that would be powerful enough to make a PS6 parity clause feasible.
they will not be able to even reach the raw power of the PS5's GPU.
this handheld can realistically maybe reach ½ the GPU power of the PS5.
the PS6 could have anything from 5x to 8x the GPU power of the PS5.
so you'd need to scale a game from a 50 tflops GPU to a 5 tflops GPU...
and developers already have issues scaling games down from 12 to 4 tflops with the Xbox Series S parity clause. yes the S also has the added issue of its memory pool, but the GPU power also often means games run sub 720p. and that's only a 3x GPU differential. now imagine a 10x differential.
it's just not realistic to force devs to do that.
mind you, I'd be all for PS6 parity! I am on record saying that I am glad the Series S exists as it keeps developers at least a little bit in check, and means by simply having to have a Series S version, most games are already equipped with a 60fps mode for PS5 and Series X by default.
if devs had to scale a game from 5 tflops to 50 tflops, we'd probably be in a situation where most games have 120fps modes on PS6 lol... and it would mean devs couldn't rely on or abuse reconstruction on PS6 either, because if the game only runs at 1080p internally on PS6, how would you scale that down by 90% to run on the handheld? wouldn't be possible.
but I know that this would get a lot of fanboys mad that the handheld "holds back" the PS6... and I think that alone means Sony wouldn't do that.