>>28799221It was about 1 month ago, but recently the guide got updated and now it's pretty easy to install A9LH into your 3DS.
Granted you've got Firmware version 9.2 in your SysNAND, it would be pretty easy to install A9LH.
Plus, A9LX + Luma3DS is much more comforable than boot to RxTools. It sure does worth the 1 or 2 hours installing it.
>>28799248N64 is a very difficult system to emulate because of the strange GPU it uses.
DS can already be run natively on 3DS - using a R4 card.
Ambassador 3DS shipped a basic GBA emulator to the 3DS, which hackers used to inject other GBA roms on it.
And as for PlayStation, I've not tested it, but there are some videos of New 3DS running Final Fantasy 7.
https://www.youtube.com/watch?v=yhyj-z4r-PU 