[avery42]

Yes. There was an experimental project called Positron [0]: "a experimental, Electron-compatible runtime on top of Gecko". It was discontinued in 2017 [1].

AFAIK the only thing around nowadays is GeckoView [2] for Android.

[0]: https://github.com/mozilla/positron [1]: https://mykzilla.org/2017/03/08/positron-discontinued/ [2]: https://mozilla.github.io/geckoview/

[pseudalopex]

There were older experiments too. Gecko Runtime Environment and XULRunner at least.