Grafava version: 5.5.0-pre
None of the app plugins and their pages are appearing on the side-menu to users who are having Viewer permission. I tested with a worldPing and Zabbix plugin. They appear only with Editors and Admin permission.
This seems to be working fine on an old version of Grafana (4.5.1)
Not sure if this is a bug or the expected behaviour is changed recently.