I am currently using an MH-M18 bluetooth audio receiver for my project.

However, the MH-M18 can only play audio, it cannot be used with a smart phone app to configure settings of my device (thresholds, volume levels etc) or firmware updates of the MCU (STM32L433).

Is there a bluettooth device available that can do both audio and connect to a smartphone app ?

This is for a battery powered, compact device so size and power consumption are important.

There are lots of bluetooth modules on the market, but they are large and complex and have lots of GPIO and interfaces that I dont require.

 

Visit your local "MICRO-CENTER" store and explain what you want. They will probably take you to the shelves where it is available. And every one of those folks are quite willing to help.
BUT you WILL need to bring lots of money. None of it is cheap.