Hi Janis, 

Luke from the Product team here. Thanks for submitting this feature request!

Is there a specific use case that our Google Ads connector can't support that you're hoping to use GAQL for? What would you use where statements for?

For context, we typically avoid adding functionality like this to our connectors because it increases complexity. We try to make our connectors as easy to use as possible for our customers. Additional configuration also comes at the cost of increased code complexity and maintenance effort. That results in fewer new connectors and features. 

You mentioned where statements. I assume you may be trying to filter the data retrieved by the connector. We believe it's better to do filtering like this in the data warehouse so that you don't need to manage the connector should your use case for the data change.