Report customization help needed. How can I get the assertion results into the report?

Question regarding reports

Currently I have some data in Excel Spreadsheet. Based on the data, I do data driven testing, each row is a test case and each test case calls multiple Apis and does some assertions after it gets the results back. I know that I can get the data from Excel in a Subreport using Datasink but how to get the Assertion results into the Subreport. The client is just interested in summary that says what was the data sent to the api i.e; Excel sheet data, what assertion step failed and why it failed.

Please advise how can I get the assertions results into a report.