I don't know if you are aware of it, but a very similar use case is met by the hovercards feature currently in beta (described here: Beta Features/Hovercards)
My team is working on improvements to the feature (tasks here) if you are interested in working together. There is also a gadget on mediawiki called "navpops" which does something similar, but has many more advanced-feature tools. It is described here: https://en.wikipedia.org/wiki/Wikipedia:Tools/Navigation_popups