SongShift, perfect for iPhone
Available for Apple devices, it allows you to connect your streaming services, stream your favorite playlists and albums from one app to another. It also allows you to monitor other playlists to update those of the new application.
The premium version allows you to share playlists and export the lists, in the form of files.
Soundiiz
This is an independent platform that allows you to synchronize, transfer from one streaming service to another, import M3U, XSPF, iTunes TXT, CSV, URL files, among others.
There is no need to download an application, because everything can be done from the website of this tool.
In the free plan, you can transfer the lists you want, but one by one and with a size of up to 200 songs. The premium plan transfers all playlists and songs at once and syncs up to 20 playlists.
Tune My Music
It allows you to go from Spotify to Apple Music, to Tidal, YouTube Music, Deezer or vice versa. In fact, this app is partnered with Deezer, to offer a better playlist migration experience.
It is the most austere app and allows you to transfer up to 500 songs with its free version, but it does not have many additional functions.