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.