I am looking for technical video projector models and screens
Do you mean already done models of a video projector/screen? If so, have you checked out and conducted a search on 3D Warehouse?
I think more of a plugin that has changeable lens distance and screen size based of users needs.
My way of working with projectors has been to draw them in and draw out “beam” lines to various screen sizes based on the information in the user manual. It’s time consuming but then you can make a component and drop it into future models, and experiment with projector positions. Look in 3D warehouse for “panasonic video projector” and you’ll see some of my models - with various degrees of sophistication! In the (current) first hit I’ve drawn in beams for the nearest and furthest zoom settings for that unit - and other lenses on other layers allowing switching between lens and zoom options to help plan the position.
This sounds like a job for Dynamic Components. I think you could set up input paramters such as lens focal length and distance to the screen and have those modify the pyramid you’ve drawn to show the beam of light from the projector. The size of the screen could be reported for the component, too. Or you could have settings for the screen size and distance and let the DC work out the required lens focal length.