Linux is a kernel (same as Zircon, the microkernel that powers Fuchsia)
The "terminal" doesn't exist. You are talking about bash, zsh, etc. these are all Unix shells (they run in a variety of OSes, including Linux, Windows¹, MacOS and FreeBSD).
The GNU core utils are opened source, so it's only a matter of time (they are available even for Windows, natively²).
¹ Bash was ported natively, zsh runs through mingw quite well.