I have their $72 Kapaxen offering for the $300? MH-26 Nikon charger for the EN-EL 18a/b battery for the d850 grip. Works like a charm. Has roughly 20 reviews on the site. Most are positive.
https://www.bestbatt.com/Nikon-MH-26-Charger-p/bbmh26.htm
Thinktank Streetwalker Pro. No question.