What does the flat line in the PWM graph for the minimum brightness mean? Does that mean there's no (or less) PWM going on at minimum brightness?

They aren't too thick if you ever used the 2000s era chocolate bar phones. Thickness is very similar though they are longer.

As a Fold3 to Fold4 upgrader, I am actually 100% satisfied with the upgrade because the increase in width on the front screen moved it from frustrating to useable. The battery life is a massive bonus, and the other incremental bonuses are what you expect. Samsung here threw in a massive tradein bonus that sealed the deal to upgrade at launch.

The changes from the Chinese manufacturers are indeed much more impressive and Samsung should be doing more to keep up but frankly they have Western markets cornered. Who wants a warrantyless Chinese import model just for some slight aesthetic improvements? So what really needs to happen is for the non-Chinese makers like Motorola or Sony to push harder rather than leave it to Samsung.

These foldables are too thick and bulky, unless there is a radical design change to slim form factor and folding ability and battery improves to let say 8000mah one can give it a serious consideration

A lot good resources are wasted on these  at the moment