+ 7
If you mean imports, I happen to think so, but never tried anything not already installed.
Runtime server limits may be an issue, and while I wouldn't know what SoloLearn would find interesting in some coder, I thought it would be better to Feedback | request a module + rally up support if you really needed something :)
If you just want to test making a module (like any library creator would do), I believe you can write a short file to disk and import it; SoloLearn will clean it up after your program exits.