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To do a 5V USB-C charger from scratch you only have to do roughly this.

USB-2.0 is even simpler, just connect power and ground, and short the data pins.

The data pin short, btw, is so the connected device doesn't try to "connect" to the power port. It detects the short (in that it simply receives every data packet it tries to send) and hence knows that it's connected to a charging port.

Yes, PCB manufacturing from scratch is a bit pricey but for something this simple it would, I think, still be in the single digits per board if you buy a small quantity. The main reason against doing that is that the off-the-shelf solution is satisfactory.

Apple products require a signal on the data pins and without it they won't charge which I discovered when I put in solar powered USB ports in our offices and den during our remodel. It was easy to remedy but a pain to have to do so. I guess that's their way of making sure you use their chargers!

Huh. Yes the D+ and D- lines must be held at 2.7V to support 12W charging (at least for USB 2.0).electronics.stackexchange.com/questions/ ... ow-are-the-d-and-d-lines-configured

Not hard; just take high precision pair of 39k and 33k resistors between 5V and ground. Or 43.2k and 49.9k, ideally.

It's not as simple as just supplying 5v. The various protocols actually adjust voltage as well. This module will only supply up to 1v below input voltage. So on a 12v car, with 14 volts input at speed, it could supply up 13volts. Which is enough to support "Super Fast Charging". On a 6v car suppling around 7.5 volts st speed, that would 6.5 volts, which supports "Fast Charging" on most devices. But that voltage increase is based upon the phone/device negotiating its supported charging protocol with the controller chip in the charger. Otherwise it falls back to 5v, which is slow charging.

On my Samsung Galaxy Ultra S24 phone, if I have it in GPS navigation mode while driving (screen on, consuimg broadbard data, and GPS receiver), the phone will drain faster than it can charge on a regular slow charger.