No, you can’t install Roon Core on a Raspberry Pi, as for that the little RPi is seriously underpowered. A RPi is used only as Roon Bridge. You need another device to install the Roon Core on, and your music would be on an internal disk on that device or on an external hard disk connected to that device, or even on a NAS device connected to the same network.
If you already have a device for Roon Core (PC, Mac, Linux server, Roon Nucleus, a NUC with Roon Rock, etc.), than you can use a network-connected Raspberry Pi and a DAC as music player anywhere on your network.