The matrix cores from RDNA5 are completely different from what PS5 Pro is using.
Last I recall PSSR is a system SDK call, not unlike how PSVR comm was implemented - ie. there's nothing saying the system must run PS5 Pro code for it. Ie. it wouldn't need 'BC' it would simply need to swap in its own upscaler - it's analogous to DLL swaps on PC.
That said - can we just
stop bending over backwards trying to retrofit the ECO mode into Handheld profile where it clearly isn't it at all?
Like litreally
nothing about how this has been implemented is even resembling a handheld-hw profile - from removal of upscalers to targeting 4k outputs and other things (like CPU spec that is overperformed by every handheld release in last 3 years including the Switch 2) - it makes absolutely zero sense and we still have youtubers bending themselves into a pretzel trying to insist
Even in this video DF is still like... but Maybe it's all there we're just not seeing it in plain sight... it's 'the powerbrick GPU' level of leaps at this point...
Idk, does Sony have a way to change a game's internal or output resolution at a system level?
They always had that in the sense you're referring to - lots of PS4 Pro games specifically ran different depending on resolution for instance.
But
neither XBox nor Playstation actually have 'system level' overrides - it's system inputs that the games decide what to do with.
Eg - 90% of PS3/360 games had a special 480p mode - for SDTV only, ie. they run better on SDTVs pretty universally (for people that complain about framerates that gen - try playing on SDTV, I mean - that's what Series S and Switch users still do in 2025 - so clearly it's 'fine').
But some games decided to downscale instead (and usually resulted in borderline unplayable results - but it was a developer choice, never system one).