Install a non-exotic alternative launcher. I use Nova, it's very similar to the Google launcher and well polished. Not sure if all vendor images allow it. I have a Moto G5 with the vendor image.

I find it quite interesting that Android even has all the interfaces and permissions to allow alternative launchers. What a great feature in this generally fairly locked-down space of non-PC OSes.

I don't know about Focus, but you can configure Firefox for Android to act as a replacement for the Chrome Custom Tabs API, which apps use to launch those mini-Chrome windows. Caveat: I use the Nightly builds, and I'm unsure how new this feature is.

Can you install add-ons in Focus? When I tried you couldn't and that made it less privacy friendly than vanilla Firefox with Ublock.