Hello, I recently made a pcb for a mini to hdmi adapter for giga r1.
The PCB is possible to get on printed for relatively cheap even though it's 8 layer. As of now, I have not tested it, and the ic for conversion would need some firmware porting based on the firmware base stm provides, however if anyone is interested in this project, I can share the pcb files here. The traces have differential routings and impedance matching done too, though I can't confirm how well would it work.