Nothing is a small start-up company, creating their own OS (even if based on Android without Google) and selling the volumes of phones they need to make a profit that allows them to grow would be more or less suicide in my opinion.
Android pretty much only works for the vast majority pf people due to the access of Google Play Services and Google Play Store, take this out and interest will simply crash and fall flat.
Take Huawei for example, the company has been huge here in Germany, especially in the years with their P20 and P30 lines of phones. Then they were hit with the Google ban and released phones without Google Play and later on their own OS, the could never recover from that to this very day here in Germany. Their marketshare fell from around 20% to 5% within a few years - not because the phones are bad, but people want to buy Android with full app support out of the box.