Various websites suck in one browser or the other or simply don’t work in more than one single browser. We’re not that far away from the days when Internet Explorer (IE) was the only thing that loaded a site (often for something work-related… groan)

That said, if you need Chrom(e/ium) and want a non-data-sucking version, I think Ungoogled Chromium is your best bet currently.

For the Firefox side of things, there are already several forks that aim to do things differently/better. Floorp is one I see recommended regularly. There seem to be a larger number of Firefox forks focusing on security/privacy than Google forks, but this is the most well-regarded from my research.

Simultaneous post-enshittification from both Chrome/Chromium and Firefox is probably (hopefully) leading towards more active development/contribution to these (and other) forks!