I completely agree that panel and live config views will be the most natural fit for a pop-out, my main concern though is going from a set dimension iframe to an iframe that has a variable size and pre-existing extensions may not be designed for that, and could lead to display bugs. So extensions that currently look polished from a user experience point of view, they could now look awful and poorly designed if the pop-out was stretched/shrunk to different dimensions, potentially even having fixed positioned elements now overlapping and blocking functionality.
At the very least I would hope that when an extension is popped out, that the new window starts off at the same dimensions as the extension view it came from.
Another example of an issue I can see happening is like my silly clicker game I threw together as a video overlay for the Extension Jam. It spawns emotes to be clicked within the iframe, if a user was to pop that out, shrink it to the size that there’s only a single space for emotes they could just spam click on the same spot, so I wouldn’t want my extension popped out at all. Technically this could be done even when not popped out, but I’ve yet to see anyone want to make their video player that small for it to be an issue. My extension also has some safeguards to prevent this a little too, but there are other extensions which would face similar issues.