I mean, you can have a custom rom on your phone etc.
The OS is not the issue. It’s that apps are exclusively distributed in the Playstore which requires a Google account to reach. People running homebrew stuff tend to use Aurora, but that app still needs Google creds to use Google’s API. The anonymous option supported by Aurora violates Google’s ToS, so it’s not a legal option that anyone could point to as an official escape from the walled garden.
I personally will not use Aurora, even anonymously, because use of the app in most cases signals to the server that they were successful in getting the app to someone and connecting. It rewards them nonetheless.
Startpage is certainly more favorable than Google. But it’s worth mentioning that Startpage is a Google syndicate so Google still profits from the use of Startpage. There are a number of searx instances out there that provide Google results by scraping Google instead of paying for API access. That’s a way to get Google results without feeding Google.