Don't mean to necrobump (okay, yes I do) ... but I installed this in my 2019 GLI a couple weeks ago. It's pretty great with a few quirks. As OP noted, the screen mirroring from your phone is rather useless, especially if you want audio -- but I wanted to point out that it's just an HDMI cable so you can plug basically anything into it ... including, in my case, a RasperryPi4b running MagicMirror2. I power it off a USB add-a-circuit stuffed in the circuit panel, it connects to my iPhone as a hotspot for internet access, and to the car stereo via bluetooth for audio out which is FAR superior to the digital console's FM transmitter.
With The RPi in there, I can now customize the digital cockpit display to be anything I want ... right now it's just Magic Mirror showing me a calendar and the weather forecast, and streaming backgrounds from Reddit's /r/wallpapers sub. In theory, I can connect it to the ODBII port and write my own custom gauges, or add a GPS module to the RPi and have a live map display on the dash at all times. Possibilities are limitless... but this ain't bad for the 20 minutes of effort I put into it.
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When I had mine, I tried plugging an SNES Mini into the HDMI port and it didn't work