Nobody to my knowledge is using more than 8 bits per color for taking photos. Certainly nobody using JPG (which includes wide-gamut JPEGs from DSLRs), and at least right now not even HEIF on iOS is anything but 8 bits. I'm guessing because it hasn't caused much color-banding for the typical use case (photos) anyways.
Sony ARW is 14 bits on the A7 line. Canon 5D Mark IV RAW is 14 bit and so is the Nikon counterpart. Even the cheap Blackmagic Pocket Cinema Camera shoots 12 bit RAW.
Why is this important? Most of these cameras images end up on the web. VP9, HEVC and HEIC all support HDR10 so with the right processing this should come through.
