Scanning for discoverable bluetooth devices with Arduino
If you can send AT commands to your bluetooth module, you can also discover nearby devices.

See for example this guide. In the example they are sending commands from computer, but you can do exactly the same with your Arduino. Sending command

AT+JDDS=0


should return list of matching devices. Additionally, you can also search for specific services:

AT+JSDS=0026C3AB5A39,1101


Where 0026C3AB5A39 is MAC address of device and 1101 is code for serial port.