Welcome to the community!
TPG do not support 3rd party router and we do not have details on how to set up Google Nest, but we do have some threads that you may find helpful. This will guide you on how to set up Google Nest, please see the links below.
Let us know how it will go and should you require further assistance.
I recently purchased Google Nest wifi and discovered I cannot use this as the primary router as does not support VLAN tagging which TPG require for authentication. I have connected the Google Nest wifi to the TP Link AC1600 provided by TPG and Google Nest Wifi appears to work however I’m experiencing a double NAT issue. I followed instructions to put the TP Link router into bridge mode however this doesn’t seem to be working correctly. Is there a way to resolve this?