Posibility to turn this into an userscript or userstyle to use on Firefox Browser

loving this so far even while running it on Arch Linux. but I would like to see the posibility of porting it as an user script or user style to apply it to the web version of spotify, even if not all themes can be used.
themes that could work are wmp11 XP, basic, classic.
you could try aero, and give it a transluscent effect that shows what's behind it, like how liquid glass on macOS does nowadays.

I think this could be possible, considering that spotify app is just a chromium app.

The issue names no files, tests, or entry points. Start by reviewing the existing SCSS Spicetify theme and how its themes are applied, then determine the scope of a Firefox userscript or userstyle and which themes can be supported; done requires that scope to be defined and implemented.

Written by the indexing model from the issue text.