While this is not exactly something to "build", other than possibly buying your own memory and SSD, but this is a very nice Mini PC from Minis Forum.
They had a Phoenix based one, with some deficiencies in terms of connectivity. The brand new model, just starting to ship at the end of July improved IO capability, mainly added DisplayPort, 2x USB4, 2x 2.5Gb Ethernet. And also, swaps Phoenix for HawkPoint 8945HS.
Operating System compatibility says Windows 11, but I wonder if Window 10 can be installed as well. Since HawkPoint has only full cores, it does not need OS scheduling.
Looking at AMD web site, it looks like AMD is supporting Windows 10 for HawkPoint.
Minisforum UM890Pro is a high-performance Mini PC featuring the latest generation AMD AI R9 8945HS processor. Equipped with the Cold Wave2.2 cooling system and a wide range of interfaces, it significantly boosts the PC's stability and robust connectivity capabilities.
store.minisforum.com