It’s the streaming company who controls what is made available to Sonos customers, so in this case, Apple is responsible for the lack of access. 

Music services are wholly responsible for their own implementation on the Sonos app.  Sonos supplies the API, the service does the work.  So since the API already supports lossless streaming from other services, it is Apple who needs to step up.

If you believe - as I do - what the head of Apple Music says, that Apple lossless cannot be distinguished from Apple lossy in a test where sound levels are accurately matched, this would be a non issue to you.

You can actually hear a difference, especially if you are using a good set of speakers with the Sonos AMP. 
I recently tried Amazon music ultimate (or whatever they call it) to test the difference. I just don’t want to move my whole family from Apple Music. 

There will be an audible difference because at the same volume control slider setting Apple Lossless is reported to yield slightly higher sound levels than Apple lossy. And slightly higher is all it takes for a difference to be heard, something that has long been taught to stereo system salesmen.