In Multi-Account reports, you can choose to see Google, Microsoft, or Optmyzr labels that have been previously created. This can be found in the Report Settings, under the Account Selector widget.
Under the "Tables" section of widgets, you can find "Labels", which will display the performance of selected campaign labels.
Amazon and Facebook
For the moment, these platforms are not supported in the label widget, however, for both Amazon and Facebook, you can set up and select an Optmyzr label to change in the account picker.