All this assuming there didn't exist an exploitable firmware in your USB chargers and powerbanks, which could be used to spread a USB virus or install a payload.
I doubt the USB data lines on a portable charger are connected to anything. When did you last update the firmware for your charger?
they might have a resistor to indicate how much current is okay to draw, or they might be hooked up to a chip negotiating things like the voltage for the pd protocol, but usually it will be an asic that doesn't even really have firmware
Not saying they don't exist, but I've never seen a power bank that had the output data lines wired up to anything.
Are there any $15 battery packs that have exposed firmware?