I can't remember the details but aparently firefox on android is not the bastion of privacy it is on the desktop.

You're best off with a chromium fork like bromite.

Also, now I think about it... I think mozilla is well meaning but they're pretty much cooked. Just a litany of errors and refusal to listen to users over the last 10 years has made their products pretty unappealing. Ads on the new tab page is a pretty good example.

Edit: the thing I was trying to remember is site isolation. Android Firefox doesn't have site isolation. Chromium does. I hate google as much as the next guy but there's plenty of chromium forks that don't send telemetry.