we am planning to procure a Xavier NX hardware for our product development and deployment. If we have a budget to purchase two units (we are working on two different projects), which combination is a better choice.
That depends on how many engineers on your product development and require to use devkit at same time and continuously to decide how many devkit required.
The module needs to work with a carrier board, and for production purpose, you need to create your own carrier board for your use case, please refer to * Product Design Guide