How to get the value inside a label or to assert is the label is not null?

We are trying to fetch a value in a label using EarlGrey. Is there any method in EarlGrey to do the same or to check if the label value is not null?

Start by reviewing EarlGrey's documented label matchers and assertion APIs; the issue names no file, test, or entry point. Confirm whether a label's value can be inspected or checked for null, and document the supported approach or limitation with a focused usage example.

Written by the indexing model from the issue text.