Jon has showed me this before, and I'm very exited!

Multiple kernels, one filesystem is the dream. We'll restore competition between kernels by lowering switching costs to zilch, finally solving the problem in the infamous Rob Pike paper (which is that the switching costs make the path dependency of "just keep working on the same legacy-constrained OS" too powerful).

FreeBSD is just the first non-Linux kernel to be done this way --- OpenBSD has been NixOS-ified too (a bit bitrotted atm though) too. Your favorite kernel can be NixOS-ified too!