Non-pressurized baskets only have one wall. You determine the pressure by varying the grind of your coffee and by varying how hard you tamp. If you use a finer grind and a harder tamp, you’ll generate more pressure as you brew. It takes practice. This is how the professional baristas do it. Trial and error. Practice and experience.
Unlike the pressurized portafilter basket, for the non-pressurized basket a finer grind of coffee may be needed. If you’re grinding your beans at home, best to have a grinder that will give you a fine grind. Going down the non-pressurized route makes tamping much more important. More work is required. It’s more about finesse. Most experts agree that if you use a non-pressurized portafilter basket correctly, you’ll get a much fuller-bodied espresso with excellent flavour.
The choice is yours.