there was some progress with the workshop support - so far I found an external tool for uploads
only one big obstacle I found is that steam likes to download the workshop stuff to it's own folder
and I need to figure out a way to grab these paths using their API etc.
(and also add support for the game to able to load maps and textures from anywhere and properly restore those in save files)
of course you can already share custom levels (the workshop is just a extra convenience)
it's just there aren't any custom maps yet 🤔
so far there is only a shortcuts.txt (it's a developer tool so there is no gui and you need to use hotkeys and built in console to do things)
I managed to make a small tutorial on how to make a pool: https://imgur.com/a/xEsuI6N
and there are several scattered replies on this very itch.io forum (feel free to ask anything yourself)
I guess I really should compile all of these together into one big tutorial some day 🤔