I used when I tried Spotify about a year ago. I used https://www.tunemymusic.com/ yesterday for Deezer and it's free. Seems to support nearly everything.In these pages, you'll find everything you need to become a pro at playlist management and favorites transfers.soundiiz.com
Give that a try with Spotify. I did something similar when I switched from GPM to Spotify a couple years ago and it was seamless.
Problem is Spotify doesn't allow for uploading your own music, and I have some tracks that aren't on any streaming service.