Standardize handling of None arguments across API calls using coerce_optional_dispatch

Currently, `None` is a valid argument for all API calls, but we don’t consistently handle it across the codebase. In cases where `None` is not explicitly supported, the function itself should take care of it internally.

To streamline this behavior, we should introduce a standardized mechanism for handling arguments. The proposed approach is to use `coerce_optional_dispatch` as a centralized solution for normalizing None inputs before further processing.

**Benefits:**
- Consistent handling of None across all APIs
- Reduces duplicated argument checks in multiple places
- Improves code readability and maintainability
- Ensures cleaner error handling and edge case management

**Action items:**
- Review all API functions for current None handling.
- Introduce coerce_optional_dispatch where applicable.
- Remove redundant argument validation logic.
- Add unit tests to confirm consistent handling of None inputs.