Great extension, thank you! One ask would be to have the viewlist use the display name which flarum now supports, there are a number of extensions that make use of using a nickname or alias for the display name of a user but this extension appears to be hardcoded to use the username.
As an enhancement it would be cool to be able to click "Latest viewers" and have it open a modal with a full list of unique views for the thread. Another would be to track unique views by username rather than IP, sometimes I have my username popup several times in a row in the latest viewers, I can only assume that is because I've viewed from mobile or desktop and my IP has changed.