I do not have any windows PC. I do not own any copy of Windows. I do not use Windows.

Every tutorial or guide I have found on how to add packages inevitably describes using this "winbox" thing. I do not have it, I cannot use it, I cannot run it.

Why is the "upload package" option missing from webfig?

How can I add a new package?

Where is this documented?

Is there a set of complete documentation, that describes all of the functions and how they are implemented in RouterOS itself, NOT locked away in some other piece of software that runs only on an OS that shall never touch anything I own?

If winbox is the ONLY way to add packages, then I consider that to be "There is no way to add packages and routerOS does not support adding packages."

That WinBox thing is really great. And while it's true that it's mainly for Windows, other OSes can run it too, Linux with Wine, MacOS with <I'm not sure what, but it's definitely possible>. Try it, it's worth it.

But WinBox doesn't have anything special when it comes to installing packages. All you need is to upload package to router (using WinBox, WebFig, SFTP, FTP, probably SMB too) and it's installed automatically on reboot.

You could probably do the same with a smart phone using the MT app................. no windows required........