It's in volume production. This is what Huawei uses for its Mate 60 phones. They've sold 30 million units. From articles I've read the features on the chip are actually quite precise, which lead people to think the yield is at least decent.
How they will get to 3nm is another question but back when Intel made its decision, 7nm was on the horizon so choosing to not go the EUV route is not as dumb as it may look now.
