Android is not at the expense of either freedom or privacy. Desktop Linux OSs come at the cost of both. It would be better to direct effort to AOSP projects as it is a much better base to build from.
AOSP is just as open-source as desktop Linux (and desktop Linux subsystems reconfigured for use on a phone) is, and has vastly better security.
People sometimes say, "maybe desktop Linux lacks in security, but its privacy is first-rate," which IMHO is silly because if your OS can be completely and totally pwned by your visiting a web page, your opening image file or your using some IDE to inspect some source-code repo, how much privacy do you really have?
GrapheneOS is just as free from data collection by megacorporations as desktop Linux is and has about 1000 times better security.