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 All the dependencies required to run ML/AI stuff became outdated, and the hardware is now basically useless.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.
Thanks for pointing that out, I must have skipped over the system76 link. You're right that besides Apple, nVidia and Ampere also make viable ARM workstation chips.
