Also FYI, there are no extension enabled versions of FireFox on iOS because Apple requires all web content to be rendered in their specified engine (WebKit IIRC) and Mozilla is not allowed to use their own.

They could still allow extensions for WebKit.

<insert snarky comment about the 12 people that's helped and get downvoted>

Firefox for Android has been downloaded between 100 million and 500 million times, which is a bit more than your estimate. :P

See https://play.google.com/store/apps/details?id=org.mozilla.fi... -> "Additional information" -> "Installs".

And given that AdBlock isn't available for Chrome on Android, I wouldn't be surprised if AdBlock for Firefox was a large motivator behind this statistic.

<insert comment about how it would be way more people if Apple wouldn't block iphone users from running browser apps>