I have created a custom row for the Entities card, which allows you to display an attribute value in the ‘secondary info’ section of an entity row. This extends the existing functionality that is currently limited to entity-id and last-changed values.
The code can be found at https://github.com/MizterB/lovelace-secondaryinfo-entity-row, and more usage details can be found in the .js file.
This is an initial release, but is working well for me so far. Now I’d like to get feedback from others. If it would be useful to you, please give it a try and let me know what you think!