Their are a number of good choices that will work in Philadelphia. The Fleming brother hibiscus seem to be popular at the moment.

Here is a link that might be useful: Fleming brothers

Is a Rose Mallow a true hibiscus?

Is a rose mallow a true hibiscus? Maybe. Rose mallow is a generic name given to several plants. Do some research by doing an advance Google for perennial hibiscus and hardy hibiscus. Exlude responses with the word althea. You can learn a lot about them. Feel free to contact me if you have more questions.

You could plant a rose of sharon bush.
They are dwarf bushes available now at the stores you mentioned.
They will bloom at the end of July til the end of September or even in October for us.
They are easy plants. Research Rose of Sharon and check out the varities that are available.
Blue satin is gorgeous!
By the way, the answer to your original question is "no".
The tropical varities must be brought indoors over the winter, and most people do. Then in May we take them outdoors again til the beginning of October.
They are worth it. They bloom in the winter too, which is nice to see in our horrible winters!
Good Luck to you!