Is there a way to add non indexed fields to a search api view?
If you were using Drupal 7 and Apache Solr, you could get something like this with the Apache Solr Display module:

https://www.drupal.org/project/apachesolr_display

The advantage here is that you can store rendered entity or entity json encoded object inside the Solr index, which allows you to access non-indexed fields. Otherwise you would need to load the node to access those fields.

I'm not sure if there is any analogous module for Drupal 8, but a similar approach might work.