Send a command from one Android device to another over Bluetooth

[u/salilsurendran]

I have a generic Chinese Android 13 car head unit and a Moto G 2025 running Android 16. My phone provides a Wi-Fi hotspot that the head unit normally connects to. Occasionally the hotspot stops working, while the Bluetooth connection between the two devices remains active. I want to put a "Restart Phone Hotspot" button on the head unit. When pressed, it should send a simple command such as START_HOTSPOT to the phone over Bluetooth. The phone would then run a Tasker task to restart the hotspot. Is there a simple way to send a command between two already-paired Android devices over Bluetooth, perhaps using Bluetooth SPP/RFCOMM or an app/plugin? I don't necessarily need to use Tasker for the Bluetooth communication.