It doesn't matter that you have 90% of all developers supporting your platform, if the final 10% is responsible for the must have apps.

Huawei had a 4% market share last year. Is that going to be enough for something like MobilePay in Scandinavia to ensure that they are present on a platform, from a company and country they don't entirely trust? Without the MobilePay app, the number of people who'd buy the phones drop to almost zero. The same happens if Danes can't use their government ID on the phones, sales drops to almost zero, because the device just lost a major feature.

I don't think it matters that Huawei has a large swath of companies ready to support their OS, it has to be all of them (or at least the right ones).

They might pull it off and get every one on board, but the investment has to be really small to justify the work for such a small user base.