I get that but I think it's not so simple in practice.
The meme at the start of this gen was that the series potato was a 1080p machine next the it's bigger cousin who did 4k.
In reality, not only is the resolution lower with series potato games, but a bunch of other graphical features.
If Sony offered a console with same CPU, same memory, same SSD, same audio tech, AI chip for PSSR, etc. BUT only had a weaker GPU, it is still possible that developers would need to adjust other graphical settings, which proves to be extra work.
I'm also not sure how much less expensive they could make it, considering it would use many same components as the regular PS5.
Their best bet would still be to lean into cloud gaming for the ultra casual crowd.