You will only be able to conduct SAR requests with the search functionality available in Archive (e.g. date range, file type, email recipient, sender etc). So you would need to know which users’ data to restore to, then search it.
If you have a request to search all users for a keyword, then this isn't CloudM Archive's purpose. It is not an eDiscovery tool. We would recommend a hybrid approach in this case.
For example, your front line workers use Archive with CloudM and Directors are given a Google AU licence so you can perform eDiscovery searches.