I have a Trekstep under my rear buimper. It helps a lot. However, I have to lube it regularly. Ice and mud clog up the works making it hard to get down. It wouldn't be at all useful for a door step because you can't get it up once you're inside and it would be very difficult to get it down before you get out.

“In a time of deceit telling the truth is a revolutionary act.”
― George Orwell

It's not over when you lose. It's over when you quit.