nvidia dgx spark?
also, system76 has one: https://system76.com/desktops/thelio-astra-a1.1-n1/configure
also, dell: https://www.dell.com/en-us/shop/desktop-computers/dell-pro-m...
HP is coming soon, will be called `ZGX Nano AI Station` apparently
Also lenovo: https://www.lenovo.com/us/en/p/workstations/thinkstation-p-s...
All of those use the same nVidia chip and the same nVidia provided Linux distro. Personally I'd be wary of spending $3500+ on a system that relies on nVidia support. They previously released an AI focused SBC, the Jetson Nano, that shipped with a custom distro based on the already aging Ubuntu 18.04, then abandoned support for it after a few years. All the dependencies required to run ML/AI stuff became outdated, and the hardware is now basically useless. It's possible to run mainline Linux on it, but you can't do anything with the GPU since that requires a special one-off driver that never got upstreamed.