So what would be a good, precision chip?
The boxes from
USA Ohm Meters are pretty good. They use China chips... but built to specification and assembled in the US. Fair pricing and good after-sale customer support.
Back when they were still Sunny
vaping, I bought several as Christmas presents for friends. Before wrapping (wouldn't want to hand out crap X-mas presents ;-)), I tested them against a Fluke 88 with a
Tech-Thing "Half-Ohm" adapter and a loaner Extech 4-wire milliohm meter.
The 'worst' one, which I kept for myself, varied 0.03Ω+/- max from my reference... the rest varied no more than 0.02Ω+/-.