Maybe I am not understanding your question correctly, but  aggregation_strategy is used to group the entities in the predictions. So removing aggregation_stategy should give you the BIO (ES) tags individually.
Take a look at the code:
Pipeline Token Classification

use aggregation_strategy instead. Whether or not to group the tokens corresponding to the same entity together in the predictions or not.
aggregation_strategy (str, optional, defaults to "none"):
The strategy to fuse (or not) tokens based on the model prediction.

If you meant something different please let me know.