I doubt it is something Thomas (marvel) would want to add. If people want to sell scripts or action parts then they can do so themselves via online script/app sharing stores - also there's the issue of them potentially becoming obsolete at some point due to changes to the engine after each update.
Also no scripts are plug & play because every project is unique, so you would most likely still have to edit scripts to suit your project/needs.
As for action part plugins, we already have a bunch of them shared & linked on the official discord server. Lehman has created a bunch of them & most recently Esmeralda has figured out how to create them & has shared a couple as well. I should probably create a page on the wiki to upload the files so they are more easily available to everyone. I'll get around to it at some point, but I'm currently working on something else.
By the way there's a new scripting language based on C# called ilios, & there's also a visual node based scripting system to go with it for people that don't want to learn scripting.
P.S: it's Lua (name for moon in Portuguese), not LUA.