Combine next-stylus, next-css, css modules and third party global css import

[mycolaos]

I'm using next-stylus with CSS modules enabled.
Need to import third party global CSS.

What is the easiest and less troublesome way of doing it?
Is there any docs that clearly explains how to handle that?

P.S.: I've searched docs, github, stackoverflow, google, whatever. I'm messing up with next.config.js. I will probably come up with some workaround, but I'm wondering if there's an easy solution hidden in plain sight?
P.P.S.: Also I'm wondering why the *.module.css convention is not implemented for the .stylus?