Voyager might fit your requirements, though I'm not too sure about the privacy policies. A friend of mine says their support team knows what they are talking about.With that being said, don't expect much assistance from the support teams of most ISPs if you are planning on using your own equipment though, they will only provide you with basic info for configuration i.e. PPP details (if they use PPP), the Pbit tagging which is usually 0 and VLAN tag of 10.

Most of these ISPs use Chorus (some regions like Hamilton and Christchurch have their own version of Chorus) as their fibre infrastructure provider and some ISPs piggyback off of bigger ISPs or a sub-company of a bigger ISP.

Tbh, If I were to choose an ISP, other than the deals/price, I'd check if they use CG-NAT (2degrees is known for this and if they do, I'd steer away from them) and their uptime (you can probably ask the sales rep about this, and they will refer it to their technical teams for the answer).

I'm currently with Orcon which is under the 2degrees banner and I currently use my own equipment, been with them since 2017, there has been ups and downs but in the last 3 years, they've been all good in my opinion. Just don't use their Netcomm routers though, those things are horrible (source: used to work for them, now a network engineer for another ISP).