the nano card holder in my iphone 11 pro is not designed to carry both nano cards

Only a selected few iPhones will hold 2 physical SIM cards. The others use an eSIM. If you did not purchase the iPhone in China, or other selected locations in that area, you have one physical SIM, the other is an eSIM.

No, the devices that use 2 physical SIM cards are designed differently. Dual physical SIM phones are not sold in the US. Does the carrier you wish to use not support the eSIM? While the iPhone 11 Pro will support 2 SIMs, one is the physical SIM, the other is the eSIM. However to use the eSIM, it has to be a carrier that supports the eSIM. Find wireless carriers that offer eSIM service - Apple Support