I have the Fenix 5x Plus and love the music. I do use Spotify and it is really easy to do. Honestly Spotify is about the best 10 bucks a month I spend. I don’t believe the watches work with iTunes directly, you will need to know where your files are and download them to your watch. It’s not difficult.

I have one and use the music feature more than I thought I would. I just download music/podcasts onto the watch and haven’t used any streaming. Having something to listen to makes long runs more bearable ;)

I use the 245 music, works great with spotify. Easy to use.

Vivoactive 4 here.... music is game changer as no more cell phone needed. Also works with Amazon music.