Thanks for sharing! I can more or less understand how it works now, but it's still interesting that you managed thought of getting the nice swirl effect just from these 2 variables. Might try to recreate it myself in Unity and stash it under my bed.
Yeah, you can check out the source on github if you want some more insight, the link is on the page and the file is called background.gdshader and is located in the scenes folder. Hope you find it useful!