Yes, that might work. Strictly, HDMI is a registered trademark that might have strings but you could always say something like EIA/CEA-861... compatible instead
trademark doesn't cover descriptive language. saying it is an HDMI port is trademarked. Saying it is compatible with HDMI cables and displays is a purely descriptive statement.
it's compliant with Valve Digital Media Interface. The fact signalling is same as for 2.1 HDMI is pure accident