Don't be so optimistic. Apple and Google are a duopoly to control mobile messaging (outside of China).
Not for me, I use a Linux phone (Sailfish OS) with no Google. Not for real activists (criminals in the eyes
es of oppressive governments like Chaina, Belarus, Russia, Iran, Turkey, ...) who will always find their way. But for 98% of any population.
It is interesting that people don't think that their western governments are oppressive too. In fact they are slowly adopting techniques used in China and other countries who try them first. People are the same everywhere. They want power and those who take pleasure from harming others get to find their way into governments.
Allowing sideloading for Android makes Google much harder to control the platform. I’d not be surprised though if sideloading would be not allowed in the future.