Android 8 and above deals with things like BLE communication differently to earlier versions (actually the way an Android "service" is managed when the app isn't running changed significantly). This is not backwards compatible.
But there are ways around this. The app itself could manage the differences, or more easily the developer can host two app downloads (APKs) in the Play Store under the same app name (Play Store sorts out which version is needed depending upon the OS version).
The Apple / Google API joint development abstracts away this complexity by managing it within the tools (as far as I understand). You simply call the new API in your app and the tools manage the nuances. Really nice as Google have already written and fully tested their code so the developer doesn't have to. Plus it helps portability between the Apple and Google platforms. I think the aim is to actually include this BLE tracking in the OS (with opt-in) so that the user doesn't need to download anything at all. But this will require OS upgrades which will take much more time, especially on Android where (generally) individual handset manufacturers are responsible for porting the latest versions onto their hardware.
BLE is fairly widespread on hardware, but there will be phones that don't have it. If Huawei phones are experiencing issues then my guess is that the lower end handsets don't have BLE or they aren't ported to Android 8 or above. Huawei had problems with the latest Android releases and Trump's trade war, they actually developed their own spin on Android using their own app store. But I think this was only really meant for the Chinese market, and I am not sure of the latest with Huaweii and Android.