Always shade thrown at "in Rust" and I don't like how it's become buzz-wordy, but here it seems appropriate- not because "oh I might use this browser because it's written in rust" more like a great resource to understand how so many various features and functionality are implemented and fit together in a particular language that might be of interest.
If this were written in D or Zig or something other than C++, I think that's unique and worth mentioning.
What a cool project to be open source. Browsers do a lot of crazy stuff.