Received the hdmi ribbon cable and assembled the case. The end result is a raspberry pi nicely sandwiched with the hdmi port and a supporting plastic piece. Used hot glue as well as strong adhesive to secure the hdmi port and this will later be covered by a black plastic faceplate:

Assembling the case was a huge task in itself but the end result became very nice and looks almost completely stock. The controller weighs in at 356 grams:

The back also looks completely stock:

Installed raspbian lite with retropie and emulationstation as frontend where the controller works well with the xboxdrv package. Also tested moonlight gamestreaming which works well in 720p over the pi zero w built in wifi. Connected with a hdmi cable and works well running only on the battery power: