I googled around and found nothing, and I would like to open my programs in VSCode or Vim. I can usually find ComputerCraft's stuff in (World)/computercraft/computer/, and I'd like to know where ( if at all ) to find the SFM programs.

It's stored as NBT on the disk. You need to use an NBT explorer on level.dat

Would there ever be plans to make it more readily accessible, i.e. via saving a copy in a directory of the world save?

yes, flat file access is on the todo list.

There will be some tedium involved in making it available to clients when on a server, but it is something I want to do and will likely explore as part of fixing problems caused by having too many labels on the label gun lol

Idea ( im not a very good developer but i tend to have somewhat mediocre ideas )

Files, logically, should be stored in the world save
I think of three possible places one could store it in terms of naming convention

(world save)/superfactorymanager/
(world save)/super-factory-manager/
(world save)/sfm/

just tossing ideas out, i like to at least try and help