With modern iPhones? I haven’t found a way that works unfortunately. Apple wants to keep their users in the apple ecosystem, so this is always going to be an uphill battle trying to work with Linux.

For music I know rhythmbox use to have good apple connectivity, have not seen it work for any of my current devices sadly.

There is a program called blue bubbles that should bring some iMessage functionality over. I have not tried it personally.

bluebubbles.app/

Sadly the best thing in my experience is to keep a mac or pc that has iTunes available for most things. Your mileage may vary though and you end up having better results. Good luck!

I'm sorry I can't help you.

But If you like Linux, sell your iPhone, buy a Pixel and install Graphene OS. It's the closest thing to a Linux phone that is actually secure, private, FOSS and daily driver worthy.

I don't have an iPhone but my daughter does.

For music I don't sync anything to her phone. I run a navidrome server and set up an account so she can stream whatever she wants whenever. I think she uses isub as her streaming app. It does allow you to download and cache files from the server to play if you are offline

As for sms, I don't know of any way to sync in Linux, but if you use Windows, the phone link app works, as several of my coworkers have set it up. I know it installs some piece of software on the iPhone you want to sync to, maybe you could do that and try running the phone link program with wine?

I also know kde connect has a link for iOS. It's not perfect but it will do the sms linking thing.