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!
I grew up elsewhere but lived in Canberra (the capital in ACT) for about 4 years. I heard about all the scary, deadly things and was a bit worried also. Long-story, short - it’s very unlikely to be an issue unless you live in certain areas.
The big funnel-web spiders are mainly an issue in an area north and a bit south of Sydney and reasonably close to the coast. I never saw one of them while living there (except in photos). My understanding also is that the spiders tend to live outside of the urban areas and more in the suburban/rural areas.
You’re more likely to get into a car accident with a kangaroo than have an issue with those big-ass spiders, from what I was told. They’re somewhat like deer in the US. But less of a joke because they are known to slash people with velociraptor-like foot naila/claws after being hit by cars and assumed to be dead by drivers who get out and check. Death by disoriented/injured kangaroo is scarier than death by spider in Australia for most, and I say this seriously!
The scariest spider stories I had… 1. out of town for several months and my bicycle had a black widow-looking (the redback, I believe) spider under the seat. and 2. one day, there was some sort of spiders born and sailing on the wind event where little spiders where everywhere (but they weren’t the Sydney funnel-web or redback spiders, luckily).