What distribution of LINUX is implemented in the MacOS Sonoma?

There is no "Linux" within macOS. Technically Linux is just a Kernel Module used to provide system drivers to communicate with the hardware of the device to allow the booting of a device so that actual applications such as text editors & web browsers can be used by a person. Even if you consider Linux to be a full fledged operating system or distribution, then it would either be running within a Virtual Machine on top of macOS (you would need to install both), or you would need to install a Linux distribution onto another partition or drive so you can dual boot the computer.

There may be lots of open source software within macOS which may have originated from Linux users or one of the other open source operating systems such as FreeBSD, etc., but they are not Linux. Plus some open source software may have been first developed on a Windows system, then later modified to run on other operating systems.

Anything that is included by Apple within macOS from the factory will automatically be patched & updated to address any bugs or security issues. When a major OS upgrade is performed (such as going from macOS 13.x to 14.x), then some apps & utilities may receive newer versions which may contain more features (sometimes features may be removed as well).

Zsh is just one of the command line shells macOS includes and is patched & upgraded the same as any other software or applications included with macOS by Apple.

The macOS operating system is a UNIX operating system with the visual interface provided by Finder (not X Window System), or the Terminal shell (UNIX command line). Apple did not include even a whiff of Linux in the macOS operating system.

You are thinking of the weasel (Windows Subsystem for Linux — WSL) that Microsoft supplies with Windows to allow one to install a Linux distribution.

ham-ster wrote:

You say "Zsh is just one of the command line shells macOS ...".

Could you tell what is another command line shells of the OS Sonoma 14.3.1, pls?

...

Here's a quick command-line intro for macOS:

... https://www.taniarascia.com/how-to-use-the-command-line-for-apple-macos-and-linux/

Here's the Apple shell scripting primer:

... Introduction

This primer is dated, is mostly bash and not the current zsh, but is still useful.

Handy reference card for zsh command syntax:

... https://www.bash2zsh.com/zsh_refcard/refcard.pdf

The macOS operating system is also known as Darwin, and the kernel as XNU:

... https://en.wikipedia.org/wiki/Darwin_(operating_system)

If you want to learn details about the kernel of macOS, iOS, iPadOS, etc:

... https://newosxbook.com/home.html

Use zsh as the default shell on your Mac - Apple Support

zsh is updated as required with macOS updates.

You can use bash if you wish, but the default shell is zsh.

To sell all available shells, cat /etc/shells