To allow your colleague to view and refresh only specific reports without giving access to the entire workspace, you have a couple of practical options. Power BI does not currently support folder-level permissions or fine-grained access within a single workspace. Instead, you can publish the required report to a separate workspace where your colleague is granted access (Viewer for view-only or Contributor for refresh capability). Alternatively, you can share the report directly from the Power BI Service using the "Share" feature this gives them access only to that report, not the full workspace.
However, for dataset refresh, they will need Build permission on the dataset and appropriate access to the underlying data source. A third option is to use a Power BI App, which allows you to bundle specific reports and securely share them with individual users, providing a curated experience without exposing other workspace content.