This is a useful ESP32 BLE tool. You can use this app to scan BLE device around you and then view services, characteristics, and descriptors provided by the BLE device. Plus, you can use it as a client to connect to ESP32 via Bluetooth, and controll the LED on DOIT ESP32 board.
To test connection with ESP32 you have to build the following example: https://github.com/Nicholas3388/LuaNode/tree/master/LuaNode_Esp32/LuaNode32/examples/esp32_ble_gatt_server_led_control_for_phone, and then download the firmware to ESP32.
The following video is a test with ESP32: https://www.youtube.com/watch?v=LhvA33yf7P8
DOIT: www.doit.am
LuaNode: https://github.com/Nicholas3388/LuaNode