Hi,
Commercial SonarQube instances have aggregation, but it’s not available on SonarCloud.
What you can do is use the APIs to pull the data you want (FYI, it will come in JSON format) and do the aggregation on your side.
The best way to master the API is to perform the desired action via the UI and eavesdrop to see which calls the UI made to accomplish the action.
You may also find this guide helpful.
HTH,
Ann