reading the Attribution IQ in the Adobe Experience Cloud help, it is mentioning Display Impressions as a touch point which can be included in an attribution model.
Is that possible at all? I thought only actual Clicks throughout the visitor journey can be captured and attributed.
That very much so depends on where the impressions are happening. If they're internal to your site, then absolutely you can include them. Impressions can also be configured for email content.
For ads being run on other domains, that would prove to be a bit more difficult, since you aren't able to send image requests to your report suite on pages you don't own.
Hope this helps!