It's fairly straightforward to add a PPA containing a normally-packaged Firefox. But it's always a bad sign when you start having to fight against the distro maintainer's choices.
Yeah, I'm used to starting with a base install and building up, I just tried out Ubuntu because I'd switched from desktop to laptop, remembered the bad-old-days of getting laptops working, and figured it would be nice to have Ubuntu handle all that stuff. But now I spend as much time bumping up against their design as I used to spend hunting down wifi drivers 10 years ago or whatever.
This is why I abandoned Ubuntu. I no longer wish to fight the system and I want to have something I can easily recommend to others. I don't want "snap" getting installed surreptitiously, that's far too much like Microsoft.
I went back to Debian in the end. Absolutely nothing wrong with good old apt. Nice to have a clean and predictable system that respects my choices.