Are there any recommended methods for pre-programming or gang programming the processors for production? Is that a feature that nVidia offers or a 3rd party can do?
Flashing or duplicating production image is usually up to how the customer chooses to do in the factory line. We do have customer using gang programmer to assist production flow. From NVIDIA ecosystem partners, you could look for hardware or carrier board vendors for the services they provide.
In our L4T BSP, we do provide multiple devices flashing feature which should increase image flashing throughput,