It’s a Bike Shuttle Trailer. This one in particular seems to be the smallest one I’ve seen so far. I have a tiny car so I don’t wanna be hauling a refurbished lawn care uhaul trailer. I want something that can carry 6 bikes and a toolbox just in case.
Found it! https://www.wsp.wa.gov/traveler/docs/cvd/170_129.pdf
This seems like a good starter base: https://www.harborfreight.com/1090-lb-capacity-3-ft-4-in-x-4-ft-utility-trailer-62665.html