I've been using Firefox on my android phones for years though, I don't remember it ever being more involved then setting it as default on the popup on first launch.
I'm pretty sure the term jailbreak comes from the term "jail" being used on FreeBSD, which iOS is based on, which is an application sandboxing tool, therefore, a "jailbreak" is a method to escape that sandbox and gain elevated permissions to the system.
iOS being a jail is a pretty apt analogy, regardless, though.
There are a bunch of apps that strictly require Chrome for their in-app custom tabs, though. I have to re-install Chrome on occasion because I can't log into apps without it. Also, having Chrome installed at all makes it impossible to NOT set a default browser (i.e. to have it ask every time), which is what I prefer since I use several different browsers for different use cases. (Note: this is on Pixel. Never had that problem on my older phones.)