Lots of easy 3 chords songs. Some are not super slow but have very infrequent chord changes.
Don't Worry, Be Happy
Folsom Prison
Hound Dog
I Saw the Light
Jambalaya (2)
C'est La Vie (2)
Proud Mary
This Land is your land
Most country is, as they say, just "3 chords and the truth" and usually slow tempo..think Cash, Williams, Creedence
If you throw in simple 4 chord progressions, it opens up even more rock/pop..there's a sticky here on UU with a list
I am a total beginner, but I was able to learn this song very quickly: https://www.youtube.com/watch?v=Y_qBwSr2WbY I'd promised myself that if/when I learned it I would let myself buy my very own ukulele, and I am now in the process of ordering one!!!