Viofo dashcams are always taking the power from the BAT wire when using hardwire kits. The ACC is only telling to the camera to work in Parking Mode or not. So you can take the ACC from fuse box.
Unfortunately, actual power packs are not taking ACC BAT and GND from the car, but only ACC and GND. This is limiting the possibilities of these power banks and complicating the hardwiring. So instead to go with 3 wires to car fuse box and 3 wires (5V or 12V) to the dashcam, appear complicated cables and limited parking mode duration based just on how much power can offer the power bank. If the power bank can offer only 15 hours in Parking Mode, your car will be protected only 15 hours.
So I will not pay $350 to any power bank which is offering just about 20 hours of parking mode for my car. I prefer to use just my car battery. Why?
On specs, the power banks are rated at about 1500 charges which means about 3-4 years.
A Varta battery with start-stop for my car, costs about $120 in my country. So I can buy 3 batteries instead of just one power bank. If a car battery is expected to be used about 2 years, this means 6 years for dashcam parking mode with car battery, with much more than just 15 hours each time with a power bank..
When a power bank will offer also the possibility to use also the car battery and not to be forced to use only the power bank, maybe I will buy one. The idea is very simple: if I will park the car everyday after coming home from work, I will use only the power bank. But if I will park the car in weekend and not starting it for 2-3 days, the parking mode will stop because the power bank will be empty. So if my car will be damaged in the second or third day this will mean that I spend $350 for nothing. And no, I will not buy 2-3 extensions and spend about $600-$1000 for a power bank.
enjoy,
Mtz