AFAICT the special Javascript APIs are implemented in Gecko itself and aren't specific to the OS. As in, if you're using Firefox right now, those same APIs exist in your browser regardless of your platform, though they may be dormant if your hardware doesn't have e.g. hardware support for vibration.

Beyond that, Mozilla's also submitting all of these new APIs for standardization, so that any app you build that uses them could potentially function in all browsers.