The Status Time Reports app has an automated migration path and can be migrated from Jira Server/Data Center (Status Time Reports version 2.0.2 and later) using Jira Cloud Migration Assistant (JCMA) automation. Be aware that Status Time Reports app's Cloud migration using JCMA is currently in beta, so you may wish to test the migration in a trial/test Cloud instance.
Items that are auto migrated
Reports
Calendars
Access settings used for displaying issue detail view
Migrating dashboards with custom gadgets from Jira Server & Data Center to Jira Cloud isn’t currently supported by Atlassian. So you need to manually create your dashboard gadgets.
If you have any questions or concerns about your planned migration to the Atlassian Cloud please contact us at support@bloompeak.io.