Seems to work pretty well so far, other than one (admittedly pretty minor) nitpick of mine. I would almost prefer, instead of requiring opening the popup from the add-on button or with a keyboard shortcut, to instead have the emoji keyboard accessible from the text field itself. A floating button perhaps, or a right-click context menu option? That would be a little more intuitive than the current system (though the current system does work fine).

(another tiny thing is that the dark theme could stand to be a little brighter, ie. dark grey rather than black, as the current is more "night mode" than "dark mode", though this is the pickiest of nitpicks and is by no means an actual problem haha)