I liked this ... didn't love it, as so many other seemed to. I feel like I'd heard nothing but rave reviews. Quite a few things to discuss (no discussion questions included, but I found some at https://www.readinggroupguides.com/printpdf/reviews/the-magic-strings-of-frankie-presto). 

This had similarities to other stories for me ... while "Music" (as the main narrator) goes out of his way to tell us/the reader, he is not "death" ... he sounds just like Death from The Book Thief. As people pop in for little interviews, it felt a lot like Daisy Jones and the Six (I realize the latter was written afterward, but I had read it first). The PDF makes the "Forrest Gump Like ..." statement, which I did think of, but also compared it to Dave Grohl's The Storyteller, which parallells it as a musical journey. SO. Many. BIG Names. (in both!)

I borrowed both the audiobook and Kindle copy from the library, and went primarily with the audio.  FULL CAST, but not really "graphic audio" ... no real sound effects and such. One thing I note is if a song is "sung" in the book, is it sung in narration? Here, it was a little of both (even with the same narrator/author). It made me wonder when it was "patter-speak" was that because a melody didn't exist? If that song was fiction, whereas others were "real" songs? 

Mentions of so many real people (in the author's note, he seems to indicate he got permission to include them). Hank Williams, Elvis, Lyle Lovett, Ingrid Michelson, many more ...   It was interesting to get the back story on the "Save the Last Dance" song (I looked it up to verify). 

As for Frankie's story ... it was interesting, but I never fully got pulled in. All the time shifts were a bit confusing to keep up with, jumping around all over. Even with the "magical realism" of Music being the narrator, and the strings turning blue, as things tied up at the end I was a bit disappointed in the required suspension of disbelief. Really?

it was ALL the nun watching him throughout his life? Setting everything up, making it all happen?

Interesting thoughts on a baby reaching out and grabbing talents that catch their eye.

The dialog was interesting in parts ... just statements ...
“Of course not.” 
“I saved a life.” 
“Of course.” 
“These pigs—” 
“Softly, Señor Rubio.” 
“This Franco—” 
“Do not speak of him, Señor Rubio.” 
“I have done nothing wrong.” 
“I understand.” 
Tears. Breathing. Silence. 
“Are you teaching him guitar?” 
“Every day.” 
“And his playing?” 
... in audio, and with different voices for different people, it didn't stand out as much, but in writing - easy to get a little confused as to who is saying what. 

No proFanity. Other words I note - cacophony

So, I liked it, glad it read it. I think I'll remember it fondly but it's not one I'd go out of my way to recommend, or track down a copy to keep in my library.