Google has paid out nearly 10 million dollars in bounties just for Chromium? Just one reason nobody else is able to compete. The money supply is infinite.
Apple and Microsoft would both consider $10m a rounding error
I would argue that you probably shouldn't be making a web browser unless you have plans to change the status quo for web browsers.
In theory, sure.
In practice, there are lany chrome forks and they all chrome with a few features on top.
In theory you can beat usain bolt by just running faster than him.
In practice nobody does.
it's irrelevant what flag your fork (nation state) flies when its marching orders come from above.
I know, it's kind of hilarious considering Apple, but it's chrome 70%, Safari 20% and the rest is various Chrome-based browsers (e.g. Edge) and Firefox with 3.35%.
So Apple has a choice of losing control of the most important app or improving their product, so there is no reason to switch. I am pretty sure they love control more than anything.