I’m sceptical of the idea that an upvote system will actually reward genuine and interesting content, particularly considering this feature extends all the way up to channels with 500,000 subscribers. The most real YouTubers are those with like <10,000 subscribers; those are the channels I would like to have suggested.
Xiaomi isn’t actually that big in China AFAIK. There is a lot of competition, not just from Apple but all the other Chinese vendors, most of whom are larger. Huawei, Honor, VIVO and Oppo all have at least an equivalent, if not larger, segment of the Chinese market.