@jamezr and other Apple Music users. Just found this and confirmed it works. Pretty cool!
Use Action Blocks, as suggested by another user, and the URL for your playlist that Apple Music can generate.
First, open Apple Music and open the main Playlist menu. Tap and hold on the appropriate playlist to open the option menu. Choose "Share" and then "Copy Link". Close Apple Music.
Install Action Blocks from the Play Store. It's a Google app. Open it and "Create new Action Block". One of the preset options is "Open a Link", although you might have to click "See more common actions" if it doesn't show in the initial set of tiles. Paste the Apple link. You will be invited to "Test" the link at this point and, providing all is well, the Action Blocks app will ask you to give the Action a name and then invite you to add it to your home screen. It's all quite intuitive.
Boom. You now have a shortcut to your playlist.
One downside is that the widget on the home screen doesn't look particularly exciting but, for my purpose at least, I don't care. You might also need to resize it but, again, I don't care because in my case the bigger the better.