Use Drupal 8 migrate API to import disqus comments from a disqus xml dump -- see https://help.disqus.com/customer/portal/articles/472149-comments-export
Instructions:
1. Export disqus comments @ https://disqus.com/admin/discussions/export/
2. Make sure the export file is named `disqus_data.xml` and move it to the same directory as this README
3. Change the COMMENT_BUNDLE constant to whatever bundle you want comments to be enabled on (we are importing for the 'blog_post' bundle) @ line 3 of disqus_import.module
4. Enable this module
5. Run the command `drush disqus-import`
6. Make sure the comment field is displayed in the "manage display" tab of your content type.