On the mill, I’m running Linux on a Raspberry Pi 4, external stepper drivers, and a control board that is supported by Remora. I have a 36V power supply, which is stepped down to 12V for the control board which feeds the RPi with 5V, and I have a touch screen attached for mill control. I have it basically working but am still tuning it, and planning to add more hardware. Probes and air control at least. I can’t easily add spindle speed control as it is, but I might gut the head and put a high-speed spindle inside instead.
LinuxCNC does take some work to get going. Remora has some sample configurations that were some help getting started, but I discovered through a little frustration that you really do have to look up what every line means in the LinuxCNC documentation and make appropriate changes. 
No, CoreXY wouldn’t have a reason to be interdigitated.
This is the “Everman” arrangement: