The reason why Brave can be Brave, is because it can hide under Chrome. Webpage owners will build their webpages Chrome-compatible, which makes them Brave-compatible, so whether they make any money off of supporting Brave is unimportant.
Mozilla can't do the same with Firefox, because they don't have anything to hide under. They rely on webpage owners making money off of Firefox, otherwise they're not going to build/test against Firefox.
Mozilla can be Brave with Firefox for iOS, and with Firefox Focus as well, because there they don't use Gecko as layout engine, they hide underneath someone else's layout engine. (Apple forces other browsers to use WebKit on iOS; Firefox Focus for Android uses Android Webview because it keeps the binary small, which is important as it's sort of meant to be a secondary browser.)
So, they're most definitely not doing the same for desktop and Android Firefox. It would kill Firefox/Gecko in no time, if they did that. It wouldn't be brave, it'd be suicide.
Apple has, well, courage to enable some anti-tracking features by default in desktop Safari. But of course Mobile Safari is so ubiquitous they know sites must continue supporting their engine.
Mozilla can't do the same with Firefox, because they don't have anything to hide under. They rely on webpage owners making money off of Firefox, otherwise they're not going to build/test against Firefox.
Mozilla can be Brave with Firefox for iOS, and with Firefox Focus as well, because there they don't use Gecko as layout engine, they hide underneath someone else's layout engine. (Apple forces other browsers to use WebKit on iOS; Firefox Focus for Android uses Android Webview because it keeps the binary small, which is important as it's sort of meant to be a secondary browser.)
So, they're most definitely not doing the same for desktop and Android Firefox. It would kill Firefox/Gecko in no time, if they did that. It wouldn't be brave, it'd be suicide.