Custom reports registration
The only report provided by the TYPO3 core is the one called Status.
The status report itself is extendable and shows status messages like a system environment check and the status of the installed extensions.
Reports and status are automatically registered through the service configuration, based on the implemented interface.
Register a custom report
All reports have to implement the interface
\TYPO3\CMS\Reports\ReportInterface.
This, way, the report is automatically registered if 
        autoconfigure
is enabled in Services.:
services:
  _defaults:
    autoconfigure: trueAlternatively, one can manually tag a custom report with the
        reports. tag:
Vendor\MyExtension\Report\MyReport:
  tags:
    - name: reports.reportRegister a custom status
All status providers must implement
\TYPO3\CMS\Reports\StatusProviderInterface.
If 
        autoconfigure is enabled in Services.,
the status providers implementing this interface will be automatically
registered.
Alternatively, one can manually tag a custom report with the
        reports. tag: