Question about Sharing some but not all between devices

This is probably a very niche question. I'm a music teacher and purchased an iPhone 12 to use as a music player in my classroom. I'm using it as an iPod essentially. I would like to share both my previous purchases on my Apple ID and Apple Music to my school iPhone without sharing everything. For example, there are certain albums I don't want downloaded on my school iPhone and I don't want my students' love of Raffi to inform my Apple Music recommendations. Same with creating playlists for myself at home and ones I use at school. I would also like to update my school iPhone via USB on my school PC as there are albums that I still have to download from CD to iTunes in order to play.

I have tried creating an Apple id using my school account and turning on Family Sharing. This made it almost impossible to get the albums I've already purchased on my school iPhone. But when I just signed into my personal Apple id on my school iPhone, it's sharing EVERYTHING. I can turn off some things like photos or messages but the playlists aren't staying with one device. Any advice? I was able to do this with the old iPod a few years ago but I don't think I had Apple Music at the time which I think is what is messing me up this go around.