I think MP3 players are a good investment, you can add whatever songs and podcasts you want for free, you can play them with the screen off for free, they don’t drain your phone battery or storage and you can pick them up for $17.
10 years ago everyone had an MP3 player, they were everywhere, and some of my most fun memories was pirating the latest song heh, a one time purchase, one thing you didn’t have though was the music recommendations, and the convience of being able to listen to any song at any time without having to hook it up to a computer and transferring files.
The high end MP3 players today run android, very thick and run off subscription services, I do wonder what’s the point in them, just use your phone. The cheap MP3 players are low quality and aren’t great. If we could have something like the ipod nano 5 with open source firmware and a replaceable battery, yeah! that woud be the perfect mp3 player in my opinion, small, slim, quality.