Man, kids these days. I say that as an adult who is genuinely jealous that I didn’t have an iPad, or one of these cool new doohickies from Kids Ride Shotgun when I was a kid.
It’s called the Shotgun Kids Tow Rope, and it basically does what you might think. Slip one end over the saddle on an adult’s bike and attach the other end to the kid’s stem. Away you go, now with less complaining from behind!
The rope itself is stretchy to avoid sudden jerks and appears to be made from high-quality materials. The line is 10 feet long and is said to be rated for loads up to 500lbs. so it could also be used to help a (very good) friend with a busted drivetrain.
Of course your grom will need to be comfortable balancing and braking on their own, and there doesn’t seem to be any sort of breakaway feature for emergency situations.