Something like this, maybe?
From https://snhackery.com/2019/08/07/configurable-data-table-widget-content-selector-part-iii/
https://developer.servicenow.com/connect.do#!/share/contents/5257137_snh_data_table_widgets?t=PRODUCT_DETAILS
You might find something of value here:
https://snhackery.com/2021/06/07/service-portal-user-directory/
https://developer.servicenow.com/connect.do#!/share/contents/5257137_snh_data_table_widgets?t=PRODUCT_DETAILS
Not documentation, but a little wizard that walks you through the values needed and then produces a sample and generates the code from the input:
https://snhackery.com/2022/05/06/sn-record-picker-helper-corrected-again/
You might find some code or artifacts in here that might be helpful:
https://developer.servicenow.com/connect.do#!/share/contents/5257137_snh_data_table_widgets?t=PRODUCT_DETAILS
