Augh, I really don't like this about Game Maker's pricing model. It effectively discourages releasing cross-platform, not for any technical reason, but just because they're holding the exporters hostage. :(
LÖVE gives you lots of nice primitives and utilities, but yeah, it leaves you to do the actual Game Stuff by yourself. Dragging things around wouldn't be too hard to build from scratch, but it would definitely take some work (and that's on top of learning LÖVE in the first place). I know dragging is possible with Ren'py, but don't know any of the details.
You could maybe build it as a web thing, with JavaScript? It sounds like you want to mostly have boxes arranged on the screen, which the web is pretty good at. You wouldn't even need a real engine; just find a tiny library that makes dragging easier and slap it on some <img> tags.