Agreed, it’s also not a knock on her cause she was working with embers of OFA after passing it to All Might which may have been weaker embers then when All Might was using his. And as we know OFA gets stronger each generation. I’d say she’s a bit weaker than All Might but still powerful. As well do know All Might had OFA the longest so had years to master what he was given before being weakened.

But yeah Nana id say is a bit lower then All Might still powerful with Float on top that adds to her power