You can get the Time in status per assignee using the Pivot Table function. You just need to do such steps:
Open a Time in Status for Jira Cloud app.
Select a Pivot Table view.
3. Then click the Fields button.
4. In the Field menu, you can customize data presentation by setting your custom fields for Rows, Columns, Report Filters. To get the time in the issue field, drag and drop such fields:
Summary or Issue Key field → Rows,
Time (hours) → Values
Status and Assignee fields → Columns
As a result, you will get the Time is status per assignees.
You can Export the customized report to Excel doc or PDF format.