Hmm yes. For such stuff a keyboard is the easiest in terms of learning the relation between chords. You also get a visual representation of chords, octaves and higher/lower notes while you listen/play.

For the very basics, I saw duolingo does a music course now. It’s very basic but it teaches notes and you get listening exercises to differentiate higher/lower notes. It’s pretty crappy for actually learning a lot but it might be a stepping stone.