Funny you should mention that! At work, we managed to find a 2U chassis that fits two mini-itx boards and flex PSUs. One board to replace a dying gateway server, and the other to play with.
Still waiting on the vendor to get the power suppies in stock, unfortunately.
Seen those chassis, I guess if rack space is at a premium then you might want that, but they make 1u servers so the 2 u two server isn’t much in terms of space saving, when you look at it that way. Have fun with it tho, its definitely going to be super niche board with main stream being at 16 core. (If we ever get Nvme NAS box might be cool for small form factor NAS but thats not going to be cheap enough anytime soon)