Coolant in Australia confirmed by Piaggio Support:
The following two products would be suitable for your motorcycle and are available from most motorcycle parts and accessories outlets, but we would recommend you have the coolant changed by an authorised service centre, locations are available on the website.
https://www.mcas.com.au/silkolene-mag-cool-1l-sk602011312?gad_source=1&gclid=Cj0KCQjwo8S3BhDeARIsAFRmkOOL9j2Oj87QQzJfLbecr-RY1LYeFXvjA6l9aL8d-8jZmN1ed8omx1MaAngaEALw_wcB
When replacing or topping up coolant it is always recommended to use exactly the same coolant that is in the motorcycle or completely change the coolant after thoroughly flushing the system to remove the old coolant as you should never mix coolant types irrespective of the colour, formulation etc.