Does this product exist?

Please post a picture.
If you see moss, it's usually indicative of soil conditions... The moss won't hurt your plants, but the soil conditions that are encouraging the moss definitely can.

I make my living making other folks' gardens look great

Hmmm...

Ok, you are operating a plant nursery...
I've seen those container plants with a bit of moss on the soil... I don't see a problem with that... I wonder if it's an indication of ph issue?

Nice looking website...

Moss generally grows in acid conditions, so try adding a little lime to the area to "sweeten" the soil.

A lot of people say that... But how do you explain the moss that shows up in the ash left after a brush pile gets burned at my house?

Moss shows up because conditions are right for it... usually compacted soil and shade.