There is no single cli command to do this.
You would need to list all dashboards:
https://docs.aws.amazon.com/cli/latest/reference/quicksight/list-dashboards.html
Grab the id’s then loop through them and run the describe dashboard definition as that will tell you the type.
https://docs.aws.amazon.com/cli/latest/reference/quicksight/describe-dashboard-definition.html
It will then be under the sheet content type: