I've heard from around forums is that custom resources are better than json files. However, I want something similar to CDDA where you can use data files from outside the game to add new content, without having PCK files and having to use the editor, can resource files be used for that purpose or not?

What I'm aiming for is a folder in my game called 'mods', each mod would have its own folder and in it could be a towers.json/tres, for adding new towers with their own costs, damage and potentially effects.

The folder would likely have to be located in user://, so user://mods/ other than that I'm not sure since I haven't experimented with this at all.