Car play - which unit to buy?

Hi guys.

I have owned a 2013 Daytona grey C7 s line since 2016. I am able to connect my iPhone via Bluetooth to play music and podcasts but am missing the visual car play experience that I’ve seen on other cars. In particular the absence of google maps on my Audi MMi screen is a big miss for me.

I’m having trouble figuring out what unit I need to buy. I’ve seen posts that indicate that the whole screen will be replaced whereas what I’m looking for is to add the visual car play experience to my existing MMI screen (mine is the type that you can open and close at the push of a button rather than being built into the dash if that makes sense).

Any idea of what exact type of model I need and where to get one? I’m wary of buying the wrong one.

thank you in advance