The Mate 10 Pro also benefits from water resistance, but elsewhere these are very similar phones, with a similar design, identical cameras and batteries and the same chipset. (t3.com)
Looking at the specs, you'll see just how similar these phones are. (android.gadgethacks.com)
While I think it is possible the feature may arrive in a future update, these are all concerns that come from releasing two similar phones within a few months of one another. (android.gadgethacks.com)