Moar progress, even if I'm a bit slow lately because of ongoing projects :
Implemented the thing as a plugin
New commands to add often used shaders
More shaders available for insertion in existing node tree, some with unique behaviors
Added something for the tidy maniacs
Finally solved something that was bothering me from a long time
Create mask directly from the active selection and (almost) never bother again with ID numbers
It works on objects and materials, and can create one mask for each selected element or a shared one
For sure it's not really useful if you can leverage Cryptomatte but otherwise, it makes the process a bit simpler and faster.