Also, as you are now going "wider" than cables and batteries etc...
There is a HUGE gap in the market for a good, reliable Apple CarPlay In-Dash double-DIN size retrofit screen.
There are LOTS of older cars out there with lousy in dash "radios". Maybe the speakers are OK. Maybe they have 3.5mm audio in. People buy iPhone-->FM radio adapters = don't work well in cities. etc
Apple Maps, Siri, etc are great. We just need an affordable in dash screen. They typical car hifi firms want $700++ for what is barely more than a low end tablet with a touch screen.
JBL had the right idea with their $400 "Legend CP100" but this never launched -- see..
See the "competition" here
Ideally, find a partner company that will do fast, affordable INSTALLATION - ideally one that comes to you. I'd happily pay to have someone install a good CarPlay (and a back up camera while you're at it) to my older but completely reliable car.