Congratulations! And thank you for the great write-up. I work with the Chromium code base a lot, and it can indeed be daunting. I use Sublime Text, which treats the code as plain text, apart from syntax highlighting. But it's also possible with at least VS Code to get some more intelligence, such as going to the definition or declaration of a function, etc.

People who have now become interested in creating their own Chromium-based browser may want to take a look at my article: https://omaha-consulting.com/how-to-fork-chromium. It gives a high-level view of what goes into maintaining a Chromium fork.