Yes, they are pretty old and not many people ever bought them. Fuhu announced larger (up to 65") meant to be HDTV (or 4K) TV replacements back in 2015 (there were plenty of pictures trying out the 65") but apparently never brought them to market. They are "out of stock" for the 20 or 24 on their website, and the price for a 20 on Amazon is even more than what the 24 on their own site was.
Apparently people DID wall mount them even though there is not a specific mechanism to do so. I think it would be interesting to try if I could find one cheap... Of course I doubt I could find one. eBay has a bunch but almost every single one has a broken screen (go figure, giant, thin tablet with glass screen might have a risk of breaking).