Based on the requirements and clarifications, here are the core classes, functions, and methods that will be necessary:

1. NutritionFactsLabel React Component: This is the main component that will render the Nutrition Facts Label. It will accept a variant prop to determine the type of label to render.

2. NutritionFacts Interface: This will define the shape of the data that the NutritionFactsLabel component expects.

3. StandardLabel Component: This component will render the standard variant of the Nutrition Facts Label.

4. build npm script: This script will be responsible for building the library.

5. test npm script: This script will be responsible for running tests.

6. publish npm script: This script will be responsible for publishing the library to npm.

Assumptions:

1. The NutritionFactsLabel component will accept a data prop of type NutritionFacts which will contain the nutrition facts to be displayed.

2. The variant prop will be a string and will default to 'standard' if not provided.

3. The build script will use Rollup to create a CommonJS, ESM, and UMD build.

4. The test script will use Jest for testing.

5. The publish script will use the npm publish command.

6. Functional purity in this context means that the components and functions should not have side effects and should always produce the same output given the same input.

7. The project will follow best practices for TypeScript and React development, including using functional components, hooks, and TypeScript interfaces for props.

Now, let's move on to the implementation of each file.

package.json