Hi,
Custom reports are currently not supported in both the AdWords and Google Ads APIs. In the AdWords API, you may only generate reports per report type as listed
here. The same applies to the Google Ads API wherein you may only query per view based on this
documentation (see
API Fields).
You may note that while the said reports may contain information on different levels or entities, the statistics are aggregated only to the specific level or entity in which the report type / view specializes in. I hope this helps.
Thanks and regards,
Peter
Google Ads API Team

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