Nightly on Android also has an option on to block Tracking (which effectively blocks also ads). That is, like Tracking Blocking in Private mode, but always "on". This option is not yet available in the non-Nightly releases.

If you do not want to use Nightly, then the normal Firefox together with the addons "ublock origin" and/or Privacy badger should not be much different than Firefox Focus, but still allow for tabs.

https://addons.mozilla.org/EN-US/android/addon/ublock-origin...

https://addons.mozilla.org/de/android/addon/privacy-badger17...