The in-app views can be Firefox by just setting it as the default browser. Lest we forget, at least Android has an actual Firefox implementation, versus iOS which does not. Not sure what you're talking about, but if you bumped into certain cases where a Chromium web view would be better for compatibility, you can use a Chromium-based fork, like Bromite, Vivaldi, or Brave, all of which can fit the bill.
The only exception I can think of is Facebook, which comes with a highly customized web view meant for tracking users, but it's not using Chrome directly. And on Android it is the custom to also allow opening links in the external browser, and even Facebook has this option (Settings -> Preferences -> Media -> Open links in external browser).
The only edge that Chrome has is the deeper integration on the "Install app" menu option for websites that integrate with SSB/PWA. Otherwise you can safely uninstall or disable Chrome completely (which I do).
I have a Samsung S21 Ultra, with 512 GB of storage. I can download torrents straight to my phone via LibreTorrent. The other day I downloaded 3 seasons of Star Trek Picard and started playing them on my TV. But first, I used Firefox with uBlock Origin installed to navigate a Pirate Bay mirror. The entire scenario is only possible on Android.