elementsFromPoint.js

//
// returns a list of all elements under the cursor
//
function elementsFromPoint(x,y) {
	var elements = [], previousPointerEvents = [], current, i, d;

        // get all elements via elementFromPoint, and remove them from hit-testing in order
	while ((current = document.elementFromPoint(x,y)) && elements.indexOf(current)===-1 && current != null) {
          
            // push the element and its current style
		elements.push(current);
		previousPointerEvents.push({
                value: current.style.getPropertyValue('pointer-events'),
                priority: current.style.getPropertyPriority('pointer-events')
            });
          
            // add "pointer-events: none", to get to the underlying element
		current.style.setProperty('pointer-events', 'none', 'important'); 
	}

        // restore the previous pointer-events values
	for(i = previousPointerEvents.length; d=previousPointerEvents[--i]; ) {
		elements[i].style.setProperty('pointer-events', d.value?d.value:'', d.priority); 
	}
      
        // return our results
	return elements;
}

Nice way of emulating document.elementsFromPoint()
I'm not sure if you're aware of this, but pointer-events inheritance can cause issues with this approach.
In this example: https://jsbin.com/larukoxoqa/edit?html,css,js,output your approach misses the p tag with purple background, whereas document.elementsFromPoint() does find the p. Since the div is found first, pointer-events: 'none' is set and this will also affect the child p, which is positioned below the div. The result is output by console.log()

From: https://developer.mozilla.org/en-US/docs/Web/CSS/pointer-events

auto
The element behaves as it would if the pointer-events property were not specified. In SVG content, this value and the value visiblePainted have the same effect.

none
The element is never the target of mouse events; however, mouse events may target its descendant elements if those descendants have pointer-events set to some other value. In these circumstances, mouse events will trigger event listeners on this parent element as appropriate on their way to/from the descendant during the event capture/bubble phases.

It seems the solution is to explicitly set pointer-events: 'auto' on all elements on the page, so they won't inherit from their parents. With a css rule * { pointer-events:auto} the p tag is not missed.