Here is how it would work:

• Add a module from A import special_operation that operates on numpy arrays and implements the operation using numpy arrays
• Add custom type annotations from A import memory_device_l1 and use it in annotating numpy arrays
• Add a plugin that implements an ASR->ASR pass that transforms all these annotations and special operations into low level C / API calls for the specific hardware API

The module A and the plugin (as an so library) will be shipped externally, not as part of LPython.

This will allow anybody to extend LPython to work for their custom hardware.