I am not sure about Python. However, you may pull an hour worth of data in Postman using the json body in the Workspace Debugger. See https://www.adobe.io/apis/experiencecloud/analytics/docs.html#!AdobeDocs/analytics-2.0-apis/master/reporting-tricks.md.

Summary Data Sources do not create visits and unique visitors. The data is processed outside a visit/visitor profile. Therefore you will not see visits/UV data against those dimensions.

Generally, this is to do with issues while installing. Can you re-install and this time while installing expand the details and see if there were any errors? 

Yes, you may bring in your hard-coded GA tags inside GA extension in Adobe Launch. You might need to work with an implementation consultant to make sure the configuration is done correctly so that you have the same data collected as from hard-coded tag from the extension.

Please share additional details so that I can get more insight on your requirement.

There is no automatic tracking of videos in Analytics. You would need to use Adobe Media Analytics extension in Adobe Launch or Media Collection APIs.https://docs.adobe.com/content/help/en/media-analytics/using/media-overview.html 

In that scenario, I will suggest using s.visitorID solution as @Andrew_Wathen_ suggested.

If you need to set s.referrer arbitrarily, use the Referrer Override field in the Analytics extension. Also, check if Internal URL Filters setting for the report suite is configured correctly.

If the cookies are being set, that means some of the code is still firing. I am not sure about the cookies created by GA extension but Adobe Experience cloud cokies are not set until they are given permission via consent management in ECID service. https://docs.adobe.com/content/help/en/launch/using...

If my understanding is correct, you are looking for overwriting existing MCID cookies on a web page when a user arrives via a mobile app. If that is the scenario, you might want to use appendToURL function along withoverwriteCrossDomainMCIDAndAID. Refer to the below docs. https://docs.adobe.com/cont...