I actually love that khaki color and my initial thought was how cool neon would look as an accent. I think it would be really cool to use different neon colors or one color of embroidery thread and needle and do either a border of stitches around all the pockets or some kind of cool pattern like the reference images below…
If neon isn’t your thing, I always love rhinestones as a fun juxtaposition to a rugged looking fabric like on your backpack. You could do sew on rhinestones and stitch them on or flat backed and use a strong glue like e6000 to get them to stick.
Hope that helps inspire you! Can’t wait to see what you do! Post a pic in this thread when you’re done!