I found this video about a product, the “Leanlever” that takes all the weight when carrying heavy loads upstairs. All the other products that claim to make lifting easier only stop the user from falling down the stairs; they don’t really take the weight of the load. This is the only one like it as far as I know. It looks like a great product that could save a lot of manual laborors’ backs.
If you’re in a hurry, he doesn’t start using the device until after 1:16. He’s demonstrating how difficult it is without it up until then!