This is a bizarre idea, but we think the Car Play Mat t-shirt by BKY Kid at Etsy actually works.
It’s part of a mini range that also includes a railroad, but does much the same thing – offering your kid a play area on your back. So you become the road or track, which they can run their toys along. What do you get? A rather nice back massage, it seems.
Various sizes of shirt available, all selling from £14.78.