Browsers seem like mysterious, undecipherable black boxes, which is very likely how G wants them to be perceived, but that is cracking by seeing the efforts/results of such projects like ladybird and others!
I hope to one day be able to jump in and contribute to break that moat! And this books looks like an amazing start!
The moat isn't caused by a lack of non-chrome browser engines, it's because so few people use a non-chrome browser engine. Firefox already exists - it's just that ~no-one uses it and for websites that don't work with it those users have learnt to just open up chrome.
I'd love for the moat to be broken, and contributing to a browser engine like ladybird would be fun - but it doesn't contribute to breaking the moat. I'd love to know what would.
What is needed to break the moat are users - and enough for website operators to care. This is what Apple/Safari has. This is what Firefox increasingly lacks.
For and for that someone will have to do something other than make a great browser.