That’s not correct. They can only support PG materials because those have known characteristics that make troubleshooting by customer support staff possible.
However, it’s just a CO2 laser - so any CO2 laser able material works and folks here can help out if you run into issues. Most people use non-PG materials in fact. There are many materials that aren’t in the PG catalog even when stocked. Glass, tile, aluminum, etc. If you’re only doing PG types of materials, there are plenty of sources for acrylic, wood and leather. Many posts here identifying different sources for different materials as well as finishing methods and masking material. PG is good for pre-masked and prefinished wood, but otherwise doesn’t necessarily provide anything you can’t get elsewhere.