[zeroego]

I don't have a novel solution to your problem, but here's my experience. I had a mac laptop for a previous job and I went down the route of using separate a iCloud account. I used spotify so it was no issue in terms of music. The company was also heavily into the Microsoft office suite of products, but I opted to not use OneNote but instead used a password protected sync-able third party note app. I did this so I could have my notes if and when I left. I personally value a clear separation of my work and personal accounts so I found this worked pretty well for me.

Perhaps you could remote into your personal mac for iMessage/Music? It would be clunky but would protect your privacy.