I think you severely underestimate the size and complexity of something like Chromium. Not every project is fork and work material.

Well, a bunch of volunteers seem to have little trouble forking Firefox and creating Pale Moon, Waterfox, LibreWolf, and IceCat. You think a government can't do that? All they have to do really is throw some money to these existing groups.

Why do you keep bringing up Chromium anyway? We're talking about Firefox here.

Yes, yes, and now Pale Moon is four years of web development out of date, Waterfox is not really recommended, LibreWolf has some sketchy history and so on. Forking is easy - keeping it updated and secure is hard.

A government funding a 1 billion dollars a year software project? That would never fly in any country.

There's no way you need $1B/year to properly fund the ongoing development and maintenance of an existing web browser. The Ladybird team is making an all-new browser from scratch for almost nothing. Just because Mozilla is wasting so much money doesn't mean you actually need that much to do the same job.