I have a TCL Android TV which has a microphone on the remote, used for Google Assistant. However, I would like to access the microphone in my app. I tried recording audio from multiple sources, like DEFAULT, MIC and VOICE_RECOGNITION, but I only got a buzzing sound.

After inspecting the Bluetooth remote, I'm pretty sure the audio is transmitted via GATT protocol (the only profile is HOGP): screenshot of Bluetooth device. Using an app I made to show all audio input devices, this is what I got: audio input devices.

I'm sure there's a way to capture the audio from the microphone, as there are 3rd party apps that do it, like SmartTube.