First thing you will want to remember is that once you start down this rabbit hole, you may not be able to stop easily.
Second thing is that I have a 2018 SEL with Sync3 and, like your larger screen, mine controls a LOT of things. You may have to get something like these so you can retain the stock head unit and get more advanced audio functions:
https://www.jlaudio.com/collections/car-audio-processors-oem-integration
What kind of speakers did you buy for your Edge? I am looking at these for mine: https://www.jlaudio.com/collections/car-audio-speakers-c3/products/c3-650-car-audio-speakers-c3-convertible-systems-99022