I understand this dis-trust of Google. Bottom line to consider is that you are always trusting someone unless you build your own devices, manage your own network, build your own software. I'm not trying to talk you out of this because I would love to see other phones supported besides those made by Google. Its probably the biggest issue with de-googled phones. Google could break these privacy roms if they wanted to. I don't see that happening in the short term but they could do it. I also believe that if they started doing things in the chips to track people, security researchers would find out and report it.

Be careful that you don't buy some cheap crap android device that is made by some no name manufacturer thinking you've escaped the eyes of the watchers. Most of the privacy issues are not hardware issues. The apps and the OS are the main issues.