This project looks great! In a similar vein, I've been using Fantoccini[0] for web browser automation task to great success! It uses the webdriver protocol under the hoods, which means it works with Chrome, Firefox, Edge (both the old and new one) and Safari.

Chromiumoxide looks like a great alternative when there is a need for deep introspection. Its API appears to be extremely complete, on the protocol level you can get access to things like the state of the webaudio engine or setup DOM breakpoints, things that are not possible with webdriver!

EDIT: forgot the link ^^'. Thx izietto.

[0] https://github.com/jonhoo/fantoccini