I was toying with the same thing for a bit - the hope was if it worked well you could build it into a little unit (audio or HDMI eARC)

Doesn't solve for single units but could help with people who use soundbars or amps

Abandoned though - was basically just multiband compression and couldn't find a way to make it adaptable enough (some media always ended up sucking)

Would be super interested to hear what you tried!