Of course it's your phone, but the whole point of using Android is that it makes a lot of choices for you. It forces a billion things on you, and this is really no different than any of the others. Everything from UI colors, to the way every feature actually works. For instance, should you be able to text message one million people at a time? You might want to, but Android doesn't offer that feature. Do you want to install spyware on your girlfriends phone? Maybe that's your idea of complete freedom, but the fact that Google makes it harder, is a good thing, not a bad thing.

If you don't like their choices, you should be able to install other software you do like. There should be completely free options that people can choose if they desire. But the majority of people just want a working phone, that someone like Google is taking great pains to make work safely and reliably.

100%. If I buy something, it's mine. I should be able to resell it, modify it, or generally work on it however I see fit. Licensed digital media bound to platforms is different (barring some kind of NFT solution?) but an OS that my phone cannot function without (and that cannot be replaced in many cases) absolutely must be under my jurisdiction.

What makes it “yours”?

You paid for it but Google still has the control. I understand that you prefers things to be different (as do I) but the reality is that we don’t have control over devices we paid for.