I can't seem to find a definitive answer ...
Can one access TVNZ OnDemand offerings when connected to Sky?
Sky abandoned their IPTV STB solution. Current premium Sky STB is either mySky HDI or + version. mySky HDi Pace box dates from 2008 so wouldn't have the capability of supporting modern streaming apps, mySky + probably not either. Maybe the Kaon box could run software supporting streaming apps but this box has no 4K ability. Sky have no such project to produce suitable software for their current STBs.
Spark FibreMAX using Mikrotik CCR1009-8G-1S-1S+. UAP, UAP AC Pro, UAP AC Pro Mesh, Apple TV 4, Apple TV 4K, iPad Air 1, iPhone 6s, VodaTV Gen 2. If it doesn't move then it's data cabled.