I am living in San Jose, and there is a peony nursery nearby: CharMarron Peony Nursery
You can google a lot of review pictures from their beautiful nursery in springs. and here is zone 9b/10a.
I talked with the owner before, and she told be without freezing month is still fine and won't impact peonies from blooming (generally peonies can live in hotter area compare to tree peonies).
I have one tree peony, two herb peonies, and one Itoh and they are doing well in San Jose city. However, they need some(just a little)shading in summer since the sunlight here is too strong which would hurt the peonies' leaf to my experience. The peonies may not perform as well as those in a colder area, but they will live and bloom anyways. Tree peonies in the U.S were originally from the Gansu province of China, which is hot and dry in summer. So I believe high temperature itself won't kill tree peony or peony.
But you need to keep in mind that rain in summer, especially a lot of rain, could kill peonies very fast. Although San Jose or Gansu is hot, but at least both places are dry in summer and have little rain. You may need to plant your peonies in the higher ground or do ridging in your garden to let the rainwater drain quickly to avoid peonies' roots from rotting if your city in Florida has a lot of rainy days in summer.
And also, the rain will damage peony flower petals and reduce your time to enjoy the blooming peony. So I think it would be very challenging to plant peonies in Florida, but you can always try with cheaper ones for a few years first before investing a lot of money in them.
Good luck
