Renderer: Specific pixel size on unknown output screen

Hello – I am coming back from node13 and am full of ideas! One project for a client will be to output a renderer on a specific pixel size.

It is for an LED wall and will be 300x200 px in the middle of the screen. The rest of the screen should be black. Unfortunatly, I still do not know the screen size of the playback computer.

Is there an option to tell the renderer to give out 300x200 pixels, placed in the middle of the screen and have the rest of the screen black? I search on the forum but was not lucky to find an answer.

Thank you!

play around with billboard transform in pixel space.