One of the first things I learned is that contraptions like this actually existed:

(Click on image to enlarge)
The image above is from an 1898 Peter Henderson & Co. catalogue (reproduced in 2002)[1], which I bought to help me identify farming implements.
We actually have a wheelbarrow seeder in the Farm Room, although it's in two parts — the hopper is on one wall and the wheelbarrow on the floor along the adjacent wall — and it seems to be missing the chain that runs through the hopper, according to this video about "Antique Broadcast Seeders": https://youtu.be/ue-IMpTgvDs.
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[1] Turn-of-the-Century Farm Tools and Implements. Minneola, New York: Dover Publications, Inc. (2002).