Andor can be watched alone. In fact, I'd almost say it should be watched before anything else as it describes the universe and sets up the conflicts in the first released film.

The Mandalorian is action/adventure but takes place after Return of the Jedi and assumes you know the world. There are tons of Easter eggs for fans, and even famous characters.

Andor is much more of a spy thriller and I can see people liking it just for what it is as it is different from most other SW stuff.

But The Mandalorian is more Star Wars. If you don't like Star Wars you probably won't like it.