Peer-reviewed paper on iOS and Android's practice of sending data from the device:
https://www.scss.tcd.ie/doug.leith/apple_google.pdf [PDF]
The go-to, default no-/low-Google choice for many:
https://lineageos.org/
The Ubuntu-based phone OS:
https://ubports.com/
The e/ foundation:
https://e.foundation/e-os/
Sailfish OS developers, Jolla:
https://jolla.com/
Calyx OS (not tested by the author/presenter):
https://calyxos.org/
enistello's choice of 'best' de-Googled phone OS:
https://grapheneos.org/
The F-Droid repository for FOSS applications:
https://f-droid.org/
The DuckDuckGo web browser:
https://duckduckgo.com/duckduckgo-help-pages/mobile/android/
