How to power a phone via PSU directly, w/out using USB with no battery / battery delete modification

I have an old samsung s6 that I want to power directly instead of using the battery for use as a car dash screen.
Reason being; I want the phone to boot instantly once it receives power.
If you charge it via usb and the phone battery is 0%, then it will take a few minutes to charge slightly before it will boot.
Which would make it annoying and slow to boot if I wanted to use it as a screen / dash in my car.
By bypassing the battery / usb charging we can make the phone get 'full' power instantly, the moment it recieves 12v from the cars ignition.
This also frees up the usb port for use with usb OTG devices (eg a car obd scanner or computer mouse)