Apart from that the other options you have, are (in random order): /e/, PureOS, KaiOS, SailfishOS, Ubuntu Touch, Plasma Mobile, postmarketOS, among others.
That's not going to be good enough for Huawei.
Similarly, all of those alternative OSes aren't going to work if they're not binary, and more importantly API compatible with Android + GMS.
The question is rather: given that it is FOSS is it good enough for them to extend the functionality on the short-term?
> Similarly, all of those alternative OSes aren't going to work if they're not binary, and more importantly API compatible with Android + GMS.
KaiOS has some compatibility (by design not fully compatible).
SailfishOS has an Android emulator. Other OSes could also use one such as Anbox.
/e/ and LineageOS are binary and API compatible with Android.
GMS is an issue, but given that Google is under a magnifying glass concerning monopoly position related to Android in EU I have some hope that alternatives for GMS (or FOSS implementations) could happen.
It's good for me¹. I want a device that does no phone home to its mothership outside my control. This requires Googles Services not to be installed.
I don't doubt that many nevertheless still use Googles Services.
¹ compared to Googles Android. I'm still desperately waiting for a device with mainline Linux support without blobs.
Will never happen.