In the past (circa a few years ago) the connection between the main board for a display and the glass driver board would be a ribbon cable, LVDS signalling. Very straightforward and typically not soldered. There'd be a ribbon cable connector. So yeah, you could just put a board between easily. And there are LVDS to H264/H265 chips already.

But as the other comment points out, older HDCP is broken wide open so ... easier to just use that. Plenty HDCP strippers on the market.