What are people who need a browser supposed to use? Chrome..? Would that make for a healthier web?

and what would that be? google with chrome? mozilla and firefox are the only thing standing between a near monopoly of google on the browser market. safari on mac os doesn't count because it is not available on other systems.

You can download browsers on Linux based on the same engine as Safari. https://webkit.org/downloads/

I was stating this when Microsoft ditched the Trident system. I don't use windows but it was the last hold out against Google completely crushing the browser market. What I didnt anticipate was just how poorly Mozilla would take the opportunity and ruin it. Nowadays the last Bastian of freedom seems to be on the Firefox forks some which are very distro specific.

How? Fork the engine or whole thing? How to pay for it? Costs many $$$ to build. Would maybe cost less without the stupid things they do but...seems a difficult calculation to make.

There are dozens of smaller browsers that don't abuse their users. When Firefox loses the mind share it no longer deserves they will finally get enough money to hire a full-time developer.

Which all use chromium, which is in practice no different to using chrome in regards to extending google's web dominance?

What's better?

No, the other way round: People who support Firefox fight the dominance of the Chromium engine. If anything, one engine dominating is bad for the Web. (There is also Safari, but for Apple OSes only.)

If Firefox was bad for Google then would Google be paying them 500m a year?

You could argue they do this in order to keep antitrust from looking at chrome too closely.

Google paid Firefox for search before Chrome even existed.

Yes, and at that point it was because Firefox was the second most popular browser. Motivations do change.

Of course but their reasoning will have changed over time. Because Firefox's market share has changed tremendously as well.