I use this one for years with ipfire. Fully supported by ipfire and enough power for virtd.
https://www.supermicro.com/en/products/system/Mini-ITX/SYS-E200-9B.cfm
But not from amazon, from https://www.digitec.ch/de/s1/product/supermicro-e200-9b-server-barebone-5813169