I think they have done a good job adding their first-party games to the NES & SNES online apps.
NES is only missing Startropics 2 and SNES is only missing Super Mario RPG.
N64 on the other hand, is missing quite a few. It's missing Wave Race 64, 1080 Snowboarding, Excitebike 64, Pilotwings 64, Mario Party, Smash Bros, Pokemon Stadium, and all of the RARE games that isn't Banjo-Kazooie.
I think they should add the Famicom and Super Famicom Fire Emblem games to NSO in all regions and ideally also the Famicom Wars games. Translated of course.
But they won't.