Awesome

Keyboard

Complex Keys

Join with text join

Mouse

Mouse does stuff.

Can work in iOS with accessibility features enabled (Assistive Touch here)

Media

Yeah...

Absolute Mouse

macOS and Windows only

Game Pad

Pairing and Programming Quirks

Supported Platforms and quirks

Android BLE HID support list

Programming and Pairing

blehid

pins=github:bsiever/microbit-pxt-blehid

Cool Ideas

Accelerometer Mouse

Computer / Phone Media Remote

iOS Camera Release

Trick: Use volume up/down

iOS Screen Keyboard

Use the Media Eject

Limitations

iOS

iOS doesn't support a mouse (well, does with assistive touch)
iOS only supports gamepad with assistive touch
iOS Doesn't honor media "Stop"

General details on HID here. Highlights: "iPhone 5s and later, iPad Air and later, and iPod touch (6th generation) and later".

Hmmm... https://support.apple.com/en-us/HT210414

Setting the pins

pins.setI2CPins(sda : DigitalPin,  scl : DigitalPin) : void

Set the Data and Clock pins.

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