Provide in-app review prompt
The amount of reviews on the various review platforms for CiviCRM is quite low (G2, Software Advice). Outside of getting partners to solicit #2 (closed) (should do at the same time they are getting reviews for their agency), I think the most efficacious would be a dismissable notification on the CiviCRM dashboard as MIH campaigns have used.
Alternatively, a less invasive option is to add a menu option under the "Support" tab.