For years I've wanted to have modern infotainment features in my Delorean. However, I don't want to go through the process to overhaul the center console with reversing the stereo & air vents or making wholesale changes to the car. What I've landed on is a portable CarPlay device. It runs off USB-C, has built-in speakers but can output via AUX or bluetooth, it's a wireless CarPlay unit, and can easily be removed when showing the car. This unit also supports Android Auto.
There's a boatload of units out there, but the one I settled on is this $80 Krunia branded 9.65" unit I found on Amazon: https://www.amazon.com/dp/B0DNZMCN1R?th=1. This size is a near-perfect width for the center console and the suction cup mount is tacky, so it grips really well onto the dashboard. The unit comes with everything and while it runs off the cigarette lighter, I've tried it plugged straight into a USB plug and it seems to work without issue.
My entire sound system in my car needs an overhaul, so I generally just use a bluetooth speaker on the shelf and use my phone for my audio. This pairs up no problem with my iPhone and speaker. The sound routes great. So if you have some form of bluetooth or AUX capability in your car, this may be the dead-simple modern upgrade you're looking for.
Here's two photos of it in my car:
IMG_0162.jpg IMG_0163.jpg