Thank you for starting this thread as I was curious about these as well.
I searched Amazon to see if they are there -- they are not. But I found several different brands of laundry sheets. A lot of good reviews. But a common complaint is that they work well as long as you don't have heavily dirty clothes, or stains that need more concentrated attention. I saw some reviews that complained that the sheets were not for people washing children's clothes since they can get the most stubborn stains.
The TS on HSN gave me pause because in the presentation I saw, the brand rep kept dipping dingy white fabrics to show how "clean" it can get very quickly. I know it would be impossible to show that on dark fabrics. But is that really clean or a bleach [alternative] effect?
Also, the rep heavily promoted their fabric softener as a separate purchase. I don't know, if I had great faith in my laundry cleaner, I'd think I could opt out of fabric softener. I use liquid detergent, and haven't used fabric softener in years, and don't need or want it (I use wool dryer balls).
So her sales pitch about the environment (less plastic bottles) and the % of water and mess of liquid detergents is totally lost by her pushing her liquid fabric softener in the plastic bottle.