Android 8.0 official version has been released for one month, but Google has not solved the issue about fragmentization and upgrading slowing. Currently, if you want to try first, there are some ways, first, users have Nexus 5X smartphone, second is to use the third-party ROM, third is to buy those Android 8.0 smartphones like Sony Xperia XZ1, etc.
About Chinese smartphones, we have confirmed some old models such as Oneplus 3/3T, Oneplus 5, Huawei Honor V9/ Play 6X can upgrade Android 8.0 by OTA.
Today Oneplus has sent out Oxygen OS new version, the version number is 1709061630, 800MB, in the update changelog, the OS can be upgraded to Android 8.0 Oreo. But those closed-in beta test users can get approved, because there are some bugs, the public test needs to wait until September.
If you want to upgrade, you need to be aware that wifi, nfc, bluetooth, etc will have some issues, the beta test stable version will be released until the middle of September. According to former analyst, Pan Jiutang, Oneplus 3 sales are only second to Xiaomi MI5 in 2016 Snapdragon 820 smartphones.