Hello,
If you are looking to run a report from the ad_group_ad level, the available attributes can be found in this guide. Upon checking, I was unable to find any dimensions/metrics that correspond to "purchase amount." However, I was able to find the following metrics:
If this is not what you are looking for, please provide a screenshot of the UI so that I can better assist you.
Thanks,
Danica Calusin, Google Ads API Team