The ACS712 hall-effect current sensor has 1 milliohm of resistance and the ACS758 has 100 micro-ohms. Those should do a decent job of measuring the current.
My LED analyzer device (Any interest in a LED/Battery analyzer device?) uses the ACS712’s. The battery path adds 2 milliohms of FET switch and two 1 miiliohm Dean’s knock-off connectors from China (real Deans connectors have around 100 micro-ohms, but cost 10 times as much). The LED path has the current sensor and two of the Dean’s-ish connectors. BTW, it’s the cheap male Dean’s connectors that have the higher resistance. The cheap females are pretty good (ahhh, if only the rest of life was that way :party: )