Is hardware video decoding supported?

Hello.

Does the platform support hardware video decoding using a library like va-api, ffmpeg or something else that is allowed in the store?

I think it uses gstreamer and that is HW accelerated via the android layer. (or something along these lines)

Android drivers, not android emulation layer to be somewhat more precise.
The two are basically unrelated, but often seem to get muxed up.