The general consensus is that it is PETG or a PETG variant. You can use PETG as support for PLA and vice versa.
Only use the Support W as the interface layer between the support structure and the part. That way, the majority of the print is what ever color the part is and only a layer or 2 is the Support W. Saves on color changes and wasting the Support W which runs out in the store very often.