I feel the ultimate solution here is to improve the role of Blueprints in UEFN. Specifically, letting us create BP’s with Verse scripts and other Fortnite-y things as components, along with all the appropriate interop of these BP’s within UEFN.
I haven’t really used the full/proper Unreal Editor much, but from what I can gather, BP’s are exactly this - they’re “templates” of composite objects. UEFN could be improved to let us copy/paste a BP from one project to another, without references being broken and such. (FWIW, in case you didn’t already know, you can “Copy” things from one Project, then open another project and “Paste” them - but this often results in broken references and such for anything more complicated than a simple object with no dependencies on another - however it does actually work surprisingly well with some specific Actor types, so I believe this functionality is WIP).
Also, semi-related, would be nice if we could have two UEFN instances or projects open at once, heh. This is probably a lot of work though, due to the cloud/games-as-a-service type of platform that Fortnite is.