There is no existing official documentation from Google explicitly detailing the lack of this feature or providing methods to implement it.
However, the absence of any relevant methods in the Google Chat API documentation and the presence of feature requests indicate that this is a limitation of Google Chat. A related feature request on the Google Issue Tracker can be found here:
You may subscribe by clicking on the star next to the issue number in order to receive updates and click +1 to let the developers know that you are impacted and want this feature to be available.
Please note that this link points to an older issue related to Hangouts Chat, which has since evolved into Google Chat. While the specific issue might be closed or merged, it reflects the historical request for this functionality. You might find more recent or related discussions by clicking the Google Issue Tracker link above.