Phonos Plus on iOS will export Sonos playlists that can be imported to Soundiiz etc. 

https://apps.apple.com/ca/app/phonos-plus/id1511326524

More detail about how to use my app (thanks @Bumper !) with soundiiz from their web site: https://support.soundiiz.com/hc/en-us/articles/360018717099-Export-Sonos-playlists-and-transfer-them-with-Soundiiz

Well worth the very very modest cost. And useful for things other than just playlists!

Hey, that’s amazing, thank you both for your replies. I’ll give that a whirl :-) 

I recently needed to migrate my Spotify playlists to Deezer, but I was worried about losing my favorite songs. That's when I found MusConvTool. The tool made the entire transfer process hassle-free. I was amazed at how simple it was to keep my music collection intact when switching platforms. If you're going through something similar, I recommend checking out MusConvTool.

I am writing this because I struggled for at least a day and a half to convert my Sonos playlists. If you research this issue you will find many who have taken even longer and still not been able to get it done.

I am moving to Apple Music. Much better quality than Spotify and less expensive, as well as more useful to me than Deezer. I had been reluctant to make the switch because of the difficulty of dealing with the playlists. Turns out it’s a breeze. There are a number of alternatives out there, but it’s a complicated issue and it’s tough to get reliability.

The way this works, at least so far, is that you need one tool to extract the songs from the playlist to a file and another to convert the songs/playlist to your desired new source. 

There are a number of file extraction programs out there, as well as some pretty complicated architectural tricks that some recommend. It can take a while to sift through these. I tried Phonos Plus first. It’s a good effort, but is limited. Won’t run on my MBPro, wrong chips, but installs on the iphone. The problem was it could only detect half the playlists and I have had no response from support in two days now. The others I tried had drawbacks as well, either incomplete execution or other complications.  I stumbled upon SonosSaver on a forum somewhere and it is a great program. Fast,  flexible, accurate, easy to use and very comprehensive...can export the music files in any of eight formats. (I found m3u extended to be most reliable for Apple Music.) Find it here:  https://sonosaver.mrupp.ch/

My Sonos playlists were a combination of uploaded ripped CDs and streamed Deezer and Amazon music files and SonosSaver handled them perfectly. Not a single issue. It finds your Sonos system and presents all the playlists. You can pick any number and immediately receive each separate playlist that you have chosen in a discreet file that can then be converted to Apple Music with a conversion app like Soundiiz, which I used and highly recommend also. It’s a great program and very popular.

The issue with the process for me was getting the playlist exported in the first place and SonosSaver did a much more reliable job than any of the competitors that I tried, free or paid. The developer has great documentation on his website and is very responsive. The free version is limited to 20 songs per list, but the registration key is very inexpensive, about $8 US. This program is just a real pleasure to use when compared to some of the gymnastics we go through trying to get a seemingly simple task accomplished sometimes.

One thing: As you know, Apple is pretty avaricious when it comes to extracting fees and since SonosSaver is produced independently, it will require a change in preferences to load the program. That is an easy and routine change to make, but of course Apple will not tell you about it. It will unpack the program OK, then messages you that it can’t be loaded because of Apple approvals. Just go to System Preferences, Privacy & Security and hit ‘Load Anyway’ and you’ve got what you need. Drop those files into Soundiiz and that’s it.

If you are interested in converting your Sonos files to any new system, like Spotify, or the notoriously touchy Apple Music, this program will save you literally hours if not days. I had 18 playlists with from 60 to 350 songs each. I was finished in an hour. SonosSaver extracted the playlists in no time. the rest time was on Soundiiz, making the conversions. Pretty slick.

Its curious/deeply suspicious how every time playlist import/export get mentioned, a new account is created on this forum and someone makes their first and only post pushing this specific tool.

@ShahidAli ‘s account was created today, specifically for this post. Hmm. And their account contains absolutely no information. If it smells like a bot, and looks like a bot, it’s probably a bot.

I’m also curious (having not looked recently) about the T&Cs around posting links, even if they’re semi related to Sonos. 

Hmm, and mysteriously the suspicious post is gone...

My guess is a moderator decided it was spam, and made it go away ;)