Amazon app store is the biggest repository of non-google dependant apps on android. 300k or something. A company with 20+ percent marketshare of europe, india and africa joining them in google free apps? Hell yeah.
If that number could get up to 700k or more, you could easily consider it a complete experience and every OEM with an interest in independence could climb on board (we know samsung wants out, no doubt microsoft wouldn't mind although hard to say if it fits with their plans).
When it comes to developers, there's really nothing more powerful than inbuilt userbase numbers. The more people in the google rebellion the better the result.
And that bent towards independance is helped a lot by the fact that the majority of google apps are pwas. So long as your platform can fully run PWAs (and I'm assuming huaweis will from their langauge on the announcement), then that brings over youtube, gmail, maps etc (as will as twitter, uber, etc)
Even if devs don't want to write their app without google dependancies, they can write is as a PWA using online google resources like maps.
If Huaweis new OS is good, and runs android apps well enough, and PWA is seemless; this is going to have a major impact on the mobile OS scene. Not least of which because they can't actually lose China (they don't use google apps anyway). It could be thoroughly rejected at first by the international market, and Huawei could keep making profit, and keep pushing it.
Having that secure market means they can make this a real long term push, like amazon did. And amazon themselves can redouble their efforts, maybe implement PWA on fireOS.
The other winning factor here is that if they go with aptoide, as they are currently working on, ANY OEM could jump on board as use the same store. Essentially it would become an inbuilt app repo, for anyone that wants to folk android, or run another OS. If for example samsung wants to jump into their tizen push, all they'd need is an android app layer, a PWA subsystem, and throw aptoide on there.