is it possible that some downstream Android "distro" will allow sideloading?

Hello,

what i mean by that is that if it's possible that some companies like Xiaomi, Realme etc will continue allowing sideloading the apps? I mean they have already modified the Android source code, how hard it could be to just allow sideloading, isn't it just something like allow_sideloading=true.

my guess is that Google services will refused to work on phones that allows sideloading, that could prevent other companies from allowing sideloading.

what are your thoughts?