Content aggregator for delivering Drupal 8 and CiviMail
You may want to have a look at this extenion: https://github.com/bjendres/de.systopia.newsstore

It can collect/aggregate content in CiviCRM, e.g. from a RSS feed. Those items can then be sent out with CiviMail. With some additional extensions you could even sent them out automatically.

I do not remember all the details and documentation is a bit sparse but probably artfulrobot could help you as he developed most of it.