Ahh! That was the missing piece of the puzzle, thank you.

Also played a bit with the Glitch import on an Elm import but found it broke npm in weird ways (something about a file being moved but not found?), but then the Github import of the same project wouldn't work either because of Node version incompatibilities that don't seem to be repl.it's fault exactly other than just "it runs node 12 and some stuff is broke on node 12".

Does look promising otherwise though, with the Nix support I can see soooo many things being possible that simply weren't on other similar options like this.

Yeah, we are really excited about the future Nix will bring for us at Replit. Soon, language version incompatibility will be a thing of the past on Replit.