I think you would stand a pretty good chance of cutting aluminum with a router as long as you had the cutter, rpm & rigidity established. From a power standpoint there isn't much difference between a handheld router & cnc spindle motor, sometimes they are one of the same. But cnc router likely would do it in several controlled depth passes so that is different chip load than plow milling full thickness & also more rigid dictated by steppers vs freehand or even following a guide template. I'd be inclined to try something like a roughing end or at least aluminum specific router endmill & not getting rammy with it. How you lubricate & evacuate chips is another consideration. For sure you want variable speed to find the sweet spot. If you google 'router aluminum' you will find some examples & maybe be in a better position to judge against your application.