While I often recommend picking up a ukelele if you're wanting a relatively easy music instrument to learn, you could argue that a steel tongue drum (sometimes referred to by other names) is an even easier way to get fantastic results. It's certainly more meditative:

C'mon, how soothing is this?

So nice.

It's maybe not quite as portable as a kalimba, but the learning curve is similar, I'd say. Creating ethereal harmonies is just so effortless, and you'll find yourself going into a kind of trance state while playing. Love it.

There are many different sizes, tunings, and octave ranges you can shop for, but for my money, a 15-note 13" drum like this one (which is $190 on Amazon and tuned to 440Hz) is a great option to start with.