A couple years ago, when writing had faded into the background for a bit, I wrote a small batch of songs, music and lyrics. I like them OK, but assume they aren't very relatable. I tend to write intellectual (not that I'm all that smart) observational pieces mostly. They're aimed more at the brain than the heart, so I've got that going against me.
They might go over better if they were dumbed down a bit, perhaps, but that's a skill I haven't practiced much.
I compose and write lyrics and I also sing them from time to time for my YouTube channel. My favorite thing to do is write songs related to my stories. It's just a little side hobby, but one of my hopes is to write a full musical version of Loyalty Fallen, the main novel I've been working on for the past couple years. I have over 40 song concepts planned for it, and so far I've finished writing four of the songs. It's a lot of fun, but I doubt I'll ever finish it.
I usually listen to audio books and sometimes narrators tend to struggle with the songs and poetry sections.
As an author if I wanted to add a song, I would probably not include it in the novel itself. I would probably post it on Youtube or other media.