Just set "apz.allow_zooming" to true in about:config. Pinch zoom works for me on macOS at least, didn't try on Windows yet. Works smoothly, just like in Safari and Chrome.
Perhaps there are still some minor bugs and they don't enable it by default?
Nice try. It works by pinching but double tap and smart zoom to cursor.
And if you zoom in somehow, you cannot pan over the page because Firefox act like you are seeing full screen and trying to go back or forward in browser history.
