Plenty of good, cheap DACs built in China (e.g. Topping) have an HDMI-shaped plug (IIS) that supports PCM-over-not-HDMI which happens to be compatible with HDMI sources, but don't dare mention HDMI because they don't want to pull in an interlocking, price-gouging nonsense from the US entertainment industry.

So you don't quite need a license for the shape of the plug, but you do need to pretend it's not something that it is.