They are scams.
Macs do not easily switch between internal and external Bluetooth radios. The HK-808 is usually used when the internal Bluetooth card has failed. Hk-808 Bluetooth Usb Adapter Driver For Mac
Look for "Bluetooth Radio" or "CSR8510 A10" (a common identifier for these adapters). If it appears here, your Mac sees the hardware. Using "BlueHDP" or Third-Party Tools They are scams
With it installed, you can access it from your Launchpad and/or put it in your Dock for future access. You know where to go to re- Instructables How to get the Ioger USB Bluetooth dongle to work on a Mac! Hk-808 Bluetooth Usb Adapter Driver For Mac