OK, so basically I am turning more and more into a gulp fan, but managed to solve things that way.
Per your post, I still made a shell script call dev.sh
In there I have all the watch files load when I run npm run dev
in my package json.
So my package JSON looks like this:
"scripts": {
"dev": "./dev.sh",
"build": ".. etc/..
}
And then dev.sh looks like this:
NODE_ENV=development concurrently "gulp watch" "npx nodemon server.js -e js,hbs,json,"
"npx parcel watch ./clientSideJS/nutritionFactsToolsJS/index.js
./clientSideJS/rankingToolsJS/index.js
./clientSideJS/ratioTool/index.js
./clientSideJS/dashboard/index.js
./clientSideJS/homePageAutoComplete/index.js
./clientSideJS/brandFoods/index.js
-d ./public/js/"
The "gulp watch"
task starts the watch for the scss conversion.
So the gulpfile.js has the following task for watching:
gulp.task('watch', function(){
gulp.watch('./public/devCSS/*.scss', gulp.series(['sass']));
// Other watchers
})
And then the scss package task is as follows:
gulp.task('sass', function(){
return gulp.src(['./public/devCSS/allPages.scss', './public/devCSS/landingPages.scss'])
.pipe(concat('SCSStest.css'))
.pipe(sass()) // Converts Sass to CSS with gulp-sass
//.pipe(cleanCSS())
.pipe(gulp.dest('./public/css'))
});
But I also like how you can call multiple tasks with gulp watch! 
In order to use gulp SCSS you need this library:
Which I now realize lists the exact example I just posted.
I also found this guide really useful:
OK, now to start writing some Sassy CSS… maybe one day I will even be writing less 