You can connect other brands on your Sony A6500. However, keep in mind that not all brands are compatible with a Sony camera. Sony cameras have a multi-interface hot shoe that does not work with Canon and Nikon flashes. If you pair them up, you won’t be able to use the features of your camera. The third-party brands that you can use for your Sony camera are Godox, Yongnuo, and Sigma. These brands have the same hot shoe as Sony.