I can't give examples (I did the work for a company so I don't own it) but starting at [0] [1] should get you to the internals. It definitely carries some risk of Firefox Nightly just randomly breaking when it updates but this solution got us beyond quite a number of bot detectors so if you're willing to risk Firefox Nightly it's possible. We didn't need nearly the flexibility something like Puppeteer has since we were injecting rrweb into the target page to record the DOM mutations and sending those to other clients.

That will give you a good start on where to even begin looking. web-ext is insanely handy for launching Firefox with a WebExtension already installed (but I did a lot of other work around this to productize the offering).

[0] https://firefox-source-docs.mozilla.org/toolkit/components/e... [1] https://firefox-source-docs.mozilla.org/overview/gecko.html