OnePlus 6T may be approved for latest version of ARCore already
ARCore updated to its most recent version (1.5 at time of writing). When Android Authority delved into its APK, they found a number of phones that have not been released yet in code related to approved devices. The OnePlus 6T (which is now reported to be launched on October 17, 2018) was on this list.
It also includes the Nokia 9; however, the release of this phone may have been deferred until 2019. It also included 2 other, less clearly-marked Nokia devices called the CTL_sprout and PHNX_sprout (or, also, possibly simply 'Phoenix'). There are also two other possible devices on the list going by Huawei's coding conventions. They are the HWJKM-H and HWLYA.
On the other hand, there are many better-known phones also named as ARCore 1.5-supported devices. They include the Asus ROG phone, numerous Samsung Galaxy models and the OnePlus flagships 3T through 6. On the other hand, the mere presence of these names in the ARCore code does not mean they have been definitively approved for the app. Then again, it is an encouraging indication that the new flagship will have the latest features from Google when it is finally available.