Android Privacy Report
This paper by Prof Doug Leith shows how great and terrible Android can be for the privacy of its users.
paper: https://www.scss.tcd.ie/doug.leith/Android_privacy_report.pdf [archive]
We find that, with the notable exception of e/OS, even when minimally configured and the handset is idle these vendor-customized Android variants transmit substantial amounts of information to the OS developer and also to third-parties (Google, Microsoft, LinkedIn, Facebook etc) that have pre-installed system apps.
It should be noted that, GApps were installed along with Lineage OS for this research. Lineage OS does NOT include Google services by default.
Notes
I used and recommend both Lineage OS and eOS. I continue to use eOS on my personal phone, OnePlus 6. Unlike in the paper, I used Lineage OS without GApps in the past, therefore without Google background services.
I am new at citing research papers. It is possible that I have made a mistake while for the citation in above quotation. If you find a mistake, please correct me, send a comment email maybe.