Is it possible to export SASS variables to be accessed within JS, without libraries such as sass-to-js?
Nope, because they don’t exist in the CSS. The values of the sass variables are just swapped in when the sass is compiled to CSS, it’s just a dead basic string replacement.
If you use CSS custom properties (ie CSS variables) instead, then yes, absolutely, but the trade-off is that they’re a bit more verbose to write.
Sass was created a long time before CSS variables were a thing, and unfortunately the two things are quite different with respect to how they work, and sass authors couldn’t just make sass variables be CSS variables once the latter were a thing.