Glad to see you're making progress on this. Once we're done exploring how fine-grained we can make the division we might want to pull back a bit and consider what logical groupings makes sense. For example, even if the float functionality can be split from the int functionality, I don't think that makes for a very logical grouping.

In addition, I don't think we want to say that e.g. pure data structures can't depend on the FFI. While their current implementation might not use the FFI, what if we want to use it in the future. We'd have to reshuffle the packages again.