Yeah, my closest site in Upper Hutt had n78 + n40 but no n5, whereas the next site over has n78 + n5 but no n40. Either way both sites seemed to have no NR-CA between the two carriers so you're stuck on either n78 OR n40 OR n5 as your NSA SCG.
Realistically the n5 isn't useful without Standalone. If you can connect to a B1/3/7 anchor then you can probably pick up n78 or n40 (especially since those come off an AAU), and if you can only pick up b28 then your phone can't do 28_n5 anyway (with very few exceptions).
