Unless I am misstaken (please tell me if I am!) it is not possible to use Liquid in SCSS.
From what I gather there are good reasons for this, so I am fine with that.
However it would very helpful if we could include different SCSS files based on some setting, for example in the config, or -hopefully- even in a data file.
Thinking out loud:
include-scss-file: (header-setting == 'header-left') ? header-left.scss : header-right.scss
Of course I am hoping for something even better than the above