To be clear, a headless system is a computer that has no screen.
So unless you really do mean that this software doesn't work on computers that do have a screen (e.g. it won't work on my Windows laptop, but will work on my Linux server that's only accessible via SSH) what you really meant to say here is that it is not available on headless systems. (I.E. It won't work on systems that don't have a screen. It will work on systems that do have a screen.)
To be clear, a headless system is a computer that has no screen.
So unless you really do mean that this software doesn't work on computers that do have a screen (e.g. it won't work on my Windows laptop, but will work on my Linux server that's only accessible via SSH) what you really meant to say here is that it is not available on headless systems. (I.E. It won't work on systems that don't have a screen. It will work on systems that do have a screen.)