Please help me rescue this sweet boy!

My sister lives in Miami and found this stray dog in her neighborhood. We believe he was dumped by his previous owners. Unfortunately she’s not able to keep him since her dog doesnt get along with others and she just does not have the space. We’ve tried calling every shelter in the area and we’ve gotten 0 responses. Hes a very sweet boy who deserves a second chance! It seems like his previous owners didn’t take the time to properly train him but he definitely has the potential. He seems to be a younger dog. Please message me if you’re able to help!