I just so happen to have been tracking mobile device market since 2004. Never-ever have I heard of something called 'OPPO' until ~2018.
Chinese players, always with the big boy pants, but not much to stuff into them.
Then you won't have heard of BBK until recently either, or maybe it's been off your radar too. As Oppo's parent company, which also owns the brands OnePlus, RealMe, Vivo, and Iqoo, BBK is the largest smartphone maker, edging out Samsung and yes, Apple. And BBK brands and devices are not sold in China exclusively, or within the Pacific Rim alone. They have global reach.