Here's how you can address your use cases:
To personalize the email using the 'accountLastFour' value from the event that qualified the user for the segment, you can use Adobe Real-Time Customer Data Platform (RTCDP) or Adobe Campaign.
With RTCDP, you can create a custom attribute in the profile schema to store the 'accountLastFour' value associated with the latest event that qualified the user for the 'Large Purchase' segment. You can configure a data ingestion rule to update the custom attribute whenever a qualifying event occurs. Then, you can use the updated custom attribute for personalization in the email journey.
For Adobe Campaign, you can use transactional messaging with event-based data. By sending event data to Adobe Campaign, you can personalize the email based on the event attributes, such as 'accountLastFour'. In case of multiple events with different 'accountLastFour' values, you can choose to trigger the email for every event, or decide on a logic to choose which value to use for personalization.
To export segment data with the 'customerID' and 'numberOfProducts' values, you can use Adobe Audience Manager (AAM) with Data Warehouse.
First, create a new Data Warehouse request for the 'Large Purchase' segment. In the request, include the desired dimensions (e.g., customerID) and metrics (e.g., numberOfProducts). Schedule the report to be generated regularly, and have it delivered to an FTP location or sent via email in a format like CSV, TSV, or JSON.
Note that this approach might not provide a straightforward way to link 'customerID' with the 'numberOfProducts' value from the qualifying event. You might need to perform some data transformation and aggregation after exporting the data to establish the desired relationship between the attributes.