Huawei just announced that it started seeding the latest version of its custom UI - EMUI 9 based on Android 9.0 Pie. But for now, it's only available in China so the international Huawei P20 and P20 Pro owners will have to wait a bit longer. Probably not that much, though.
For now, there's no word on when the new update will hit the international variants but it probably won't take that long since the Chinese stable version is currently rolling out.
Source (in Chinese)
Lies and more lies... "global rollout" .. yeah.. right... how come my P20 didn't received it yet?
will it arrives in p20 lite