No you need to buy usb connector to solder yourself if you want do that.
First of all, that's trivial to do (don't see the issue) and secondly, you can use any type of connector to provide the extra power. It could also be feasible to solder thick wires with USB-A on the end, though, I suppose.
In case you want to do this, I have to revise what I said about soldering to large VDD and GND planes: the ones I thought about are obviously not at the right potential and would skip the power regulator circuit, so you need to solder to the existing USB connector's contacts (plus side: they're nice and big).
Low voltage has a lot of losses on small section cables.
Yes, you need thicker cables due to high power. So what?
2.4-3A isn't within specifications need an USBC connector for these type of power delivery and it's add a huge layer of complexity.
That's wrong. 2.4A is definitely in spec. All my mobile devices are charged at 2.4A through USB-A - I think it's the USB PD 2.0 spec or something like that (commonly known as 'fast charging').
If you want to go higher, of course that's outside the specification, but that's why I said that sidehack makes these with 2.4A in mind.. of course you can overclock higher if you provide more power through specialized hubs, but you
could run them in-spec.
It's why all usb devices USB 1.0/2.0/3.0 consuming more power than about 0.9-1.5A have an external power supply connector for stay within standard.
Look at your phone. It has a single USB connector without external power supply, yet it charges at 2.4 Amps on a normal modern phone charger.
You have a certain number of stick aligned with your cooling/power supply/cable/custom design but in 2/3/5 years where are too weak you trash all these stick and replace them without change anything just solder the 2 wires on the new stick but keep all other part forever. Each part are independent and can be replaced but designed for your power available. Change nothing if you have 50W/100W/1000W solar panel power and can consume exactly what is available and you can even easily control each stick with relays.
Okay, so the idea is to keep the lower part of the stick (power supply circuit). Not sure that's going to save you that much money. Also it is virtually the same as in Compac, NewPac, 2Pac, but it is slightly tuned to the chip(s) that it powers, so they would need to make it somehow modular (
move resistor to change core voltage and similar), and I'm not sure it makes sense to save at the very most $10 off a $250 device.