I don't know where your mistake is. My guess at this point is there's a problem with your SD card, and I would try setting up a new SD card from scratch in order to see what happens.
Ok so after re-doing all the previous steps, then booting into Hekate then Fusee-Primary THEN use NSA installer I installed a game then booted, got a black screen, hard reset my switch and now the game works?
I don't know where your mistake is. My guess at this point is there's a problem with your SD card, and I would try setting up a new SD card from scratch in order to see what happens.
If he's using fusee-primary, that shouldn't matter.
Once again I fell down the martial arts rabbit hole and am plumbing the murky depths of the internet's various martial arts and fighting crafts echo chambers.
If you're not actively involved and only get up to speed every few years or so, you can see the tide of public opinion flapping worse than my dong while I'm skipping naked down a hallway.