There is no Mini-ITX for Threadripper, but there is MicroATX already - HWCooling.net
Used Mini-itx For Asus Rog Strix X570-i Gaming Motherboard Socket Am4 For Amd X570 Original Desktop Pci-e 4.0 M.2 Mainboard - Motherboards - AliExpress
All the best mini-ITX motherboards for Ryzen, Threadripper, Coffee Lake and Skylake-X - YouTube