[smlavine]

I use Firefox on Android perhaps entirely because it supports uBlock Origin and my other extensions.

I would guess that of people that would ever go out of their way to use a non-Chrome browser on Android, the fraction who care about extensions is pretty significant.

[seltzered_]

On a different tack, I feel like I went out of my way to use Firefox (and Firefox Focus) on iOS and was thankful they had them during a time where everything had to use the safari renderer. IIRC Firefox Focus even had an ad-block extension that worked on safari

[thisislife2]

Firefox / Focus (like all browsers on ios) actually uses the "Safari renderer" (WebKit) because Apple doesn't allow any other browser engine on ios.

[umanwizard]

I would agree that it's probably significant. But it's probably not so high that a non-extensions-enabled Firefox for Android wouldn't be useful.