I’m sorry, but the knowledge sources don’t explicitly say whether the table-only view of the Retention cohort grid can be shown on a Board.
What they do confirm is:
- The Retention “Retention Curve” visualization always includes both a line chart and a table; the data is identical between the two. [Retention basics]
- Reports (including Retention) can be added to Boards as report cards, and Boards support multiple visualizations and layouts, but there’s no specific mention of a “table-only” Retention card option. [Boards quick start]
Because the docs don’t state that you can switch a Retention report’s Board card to show only the table (like Insights’ table chart), I can’t confidently say that this is possible based on the provided information.