Sharepoint Data with Oracle Data

There are a few things going on here.

You are using Value.NativeQuery but without specifying your folding intent. That makes it ineffective.

You are specifying both a query and HierarchicalNavigation=True.  That doesn't go together, and you should set the navigation to false

You are combining an on-premise data source with a cloud data source.  This mandates that your cloud data source needs to be accessed via a gateway connection.  Your gateway needs to be configured accordingly.

You chose to ignore privacy settings. That is not recommended. Better set both to Organizational.

As to what gets executed first - that is up to Power Query to decide.  If you want to enforce things you may need to use Function.InvokeAfter() in a slightly quirky way.