The Thompson HTML/CSS contains views which have not been implemented in the theme yet. For this view the featured items blocks need some additional features.
Add a "Link text" to the item options of the block
Rename block-bundle\Resources\views\themes\default\blocks\featured_items\index.html.twig to default.html.twig (to be consistent with other blocks)
Support the "Link text" in the default view (replace "Read more")
Move the Text to an editor (like /admin/block/new?class=Integrated\Bundle\BlockBundle\Document\Block\TextBlock)
Support HTML for the text field in featured_items\default.html.twig
Place the block somewhere with the default theme
Do all fields work correctly when editing a block?