[Feature]: support nlayers to support load a small model for debugging

### Feature Description

As models continue to grow larger, debugging with the entire model becomes increasingly difficult and time-consuming. It would be helpful to support an additional argument that allows loading only a specific part of the model, making it easier to isolate and debug issues.

### Motivation and Use Case

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### Alternatives Considered

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### Definition of Done

_No response_

### Additional Context

_No response_

The issue does not name any files, tests, or entry points, and its Definition of Done is empty. Start by locating the existing model-loading path and determine how an nlayers argument should select a partial model; done should include loading a smaller model portion for debugging and validation of that behavior.

Written by the indexing model from the issue text.