An idea from רונאלדיניו המלך, a contributor, "Consider adding a small icon to indicate whether the article is featured or not.".
Perhaps pulling the article quality via Categories or even future ORES support?
On English Wikipedia, you can pull article quality from the PageAssessments API: https://www.mediawiki.org/wiki/Extension:PageAssessments#Pageassessments
FWIW, I think this idea is interesting, but potentially feature creep.