Suggestions for improving the handling of local mods

I remember talking about this a bit in the Matrix room, but I thought I should make an issue here to get all the ideas into one place.

Handling local mods with Portmod is fairly easy, but not nearly as easy as just installing a mod from the repositories. Unfortunately, local mods are a fact of life because there are so many mods it's impossible to get them all into the repositories. I still think the workflow could be improved.

For one, improving importmod to be more end user friendly would be helpful. Instead of the current workflow of

1. Download mod
2. Move mod to pkg/local and extract
3. Figure out which plugins and optional files you want
4. portmod <prefix> merge --sort

The workflow could be something like

1. Point importmod to a URL
2. importmod could possibly parse the files list to find optional files and then maybe come up with flag names?
3. Have an interactive interface where importmod asks you which options you want
4. Those options get added to package.use

These are by no means finalized ideas, and I'm not even sure how feasible they are, but I just wanted to brainstorm.