use ‘policy plus’ and disable windows update

Correct me if I’m wrong, but can’t this be used as a precedent for other app makers that are screwed over by google’s monopoly?

If I download the latest software update on my s23 ultra, I will no longer be able to sideload?

Out of the loop here. How can google lockdown an open-source operating system? I know they are involved in developing it because it benefits them, but does that mean they own it?