There is not an ISO provided without desktop mostly because it would need an installer from terminal. For a headless installation the available options are rootfs-base archive and the docker image.

I don't think we understand each other here: are you suggesting that there must be a desktop to use a graphical install? It is possible to graphical install with calamares a system without desktop.

Typically, I rent a VPS, connect with VNC and install a minimal system graphically, then ssh only.

Calamares installs by cloning the squasfs which runs the ISO image. Either it is not possible or I don't know how do what you say with Calamares plus it has not been a priority for openmamba so far.

Yes, I think you're right. I was mistaken about Calamares, I apologize.

I would like to use openmamba as a server OS, but I need a more minimal install solution due to my current provider's limitations on ISO size and storage, and lack of graphical acceleration.