I built one out of the 1/2" foam insulation board from Home Depot. Got the stuff with aluminum foil on both sides (radiant barrier). It's easy to make for the 2019 because the sides are straight back and it can be easily removed by just pulling it straight out to the rear, unlike the one in my 2015.
I cut it to size and then used Gorilla duct tape on all edges, to keep it from coming apart. Then painted the whole thing with PlastiDip to make it match the black interior of the car. It works great and was only about $20 to make. This is just the beta version. I'll use it to make the next one.
Since it's foam board, it doesn't hurt the forehead if you bump into it. Also, I haven't rigged up the pull cords or axis parts yet, so I just lift it up and slide it down in between the protruding axis pins and the support rail. It's light enough that it sits there, wedged in place... and out of the way.
If I like this well enough after the test period, I'll build the final version. If not, I'll order the real deal from some OEM company.
One other thing: I had a problem with my forehead hitting the one in my 2015 Leaf. It was a very hard and coarse material edge and it cut my head on a few occasions. I eventually got a roll of rubber edging, cut to length, and put two strips on the cover. It protected my forehead on numerous occasions and encounters with that stupid cover.
President and only member of the Machine Gun Toting Electric Scooter Riders club, Texas chapter.