For those unaware, YouTube has a list of signature devices that support all of YouTube's features. Features like HDR, 360-degree video, 4K decoding, high frame rate, Google's VP9 profile 2 decoding and DRM support must be possible to be included in the list.
That's quite a tall order, which is why the smartphones listed are supposed to be able to help you be the next best YouTuber. The list was recently updated with the addition of the Huawei P30, P30 Pro and the Honor View20.
Other smartphones listed also include the Huawei Mate 20 and Mate 20 X, the Samsung Galaxy Note9, S9 and S9+, and even the Sony Xperia XZ3. For a full list of the devices, you can go to their official website.
You would think that being on the list means these smartphones are the best of the best, but so far reports have shown that just because these features are possible, the quality of the output may not be the best. It's also important to note that most of them aren't all that hard to support anyway, except HDR which requires HDR-compatible display.
So even with this recommended list, you probably shouldn't trust it too much. Looks like it's up to us at Stuff to figure out whether these smartphones really are the best in utilising YouTube features.