Honestly, Chromium seems to have the basic features like history and passwords figured out way better than Firefox (or rather, Chrome does), while stripping most of the junk away, as it luckily happens to be proprietary Google bullshit.
Firefox has a bunch of telemetry and bloat, but the fact that my only real dealbreaker for a browser is quality adblock makes Firefox pretty much my only "vanilla" choice.
So a post-apocalyptic fantasy rural frontier/urban civilization center split is fully within the realm of.possibility.
With US cities and states beibg pretty autonomous most things considered (for now at leas), it could easily happen without the US splitting as far as the world map goes.