I place no money on the following, but.....
I have been told (and the installers that did our UFB install last year also repeated it), that there is a preference that the ONT be very near your main TV. The thinking being that the biggest hog of data is likely to be your home entertainment. This actually worked out pretty well for us and the "home entertainment stuff" has a cable connection.
But I can also understand why you may want your ONT elsewhere. I dont know how much negotiation rights you have on positioning or whether it would be easy to achieve at your place - can you get easy access under the house for example?
This is all I can find on the chorus page:
https://www.chorus.co.nz/help-and-support/fibre-installation/what-ont-and-where-should-i-install-it
What is an ONT and where should I install it?
An ONT is an Optical Network Terminal. This device connects the fibre that has been wired the outside of your house, to your modem.
The ONT is a small white plastic box (180mm x50mm x 120mm) that will be placed on your internal wall.
It’s important that you think about where the ONT is placed before our technician arrives for your 'Agree' appointment as this can impact your broadband experience. Your modem will plug into your ONT so it should ideally be:
where you’re using the internet the most.
centrally located in your home if possible as that’s how your WiFi works best
accessible to Internet heavy-devices such as televisions.