As a counterpoint, I’ve had Ubuntu’s installer and grub’s updater overwrite and break Windows’ boot files several times, but never had the opposite happen (I’ve had both destroy themselves, though). Thankfully, I know how to rebuild the necessary parts of a Windows install, so it’s never been a catastrophe, but it’s irritating to see what’s always been the source of the problems I’ve had be held up as infallible. Possibly this is a problem unique to Ubuntu - I’m happy to blame Canonical - so maybe it could be entirely sidestepped with other distros.
Upstream Firefox doesn’t comply with FDroid’s rules (thanks to the ‘proprietary bits and telemetry’ Handles mentioned), so is only available from the Play Store or as a loose APK that won’t auto-update.