The standard charger is 2.5W, not 5W, and RPi3 will happily run from that, for RPi4 2.5W is somewhat marginal, but it will still work. I suspect that RPi5 is going to be somewhere around 3W (non-PD USB3).
The official RPi specs intentionally overblow the power consumption in order to provide an buffer for powering whatever ridiculous stuff people may hang off the USB ports.
Then the other issue is that all RPis need somewhat tighter voltage tolerance than what is in USB specification. So it is perfectly possible that a cable between the power supply and RPi is compliant, but has too large series resistance on power lines for RPi. And well, powering RPi from random aliexpress-grade “Android chargers” is completely another bad idea.
I meant “standard USB charger” from your pile of random chargers, not the one that RPi Foundation sells. Such a thing hopefully provides the 500mA, that the USB2 port is supposed to deliver.
The official RPi specs intentionally overblow the power consumption in order to provide an buffer for powering whatever ridiculous stuff people may hang off the USB ports.
Then the other issue is that all RPis need somewhat tighter voltage tolerance than what is in USB specification. So it is perfectly possible that a cable between the power supply and RPi is compliant, but has too large series resistance on power lines for RPi. And well, powering RPi from random aliexpress-grade “Android chargers” is completely another bad idea.