On 16 August 2022 the CAA released Revision 3 of NTC91258 - ADS-B Systems Notice of Requirement. 

The primary purpose of the latest revision is to allow glider maintenance engineers (authorised under Part 149 by a gliding organisation) to install ADS-B systems on gliders only. 

The latest revision, plus the summary of public submissions, can be found here - CAA Notices | aviation.govt.nz