Well, you
can install homebrew,
but you cannot downgrade to 9.2 and install unlegit cia's. So I guess you want Homebrew to install illegal games, but unfortunately you're out of luck because you're on 10.5. Your best bet is going with Sky3DS+ as it uses .3ds files and can play all the latest games. It's really like one of the "old" R4 cards, just copy paste it and you're almost ready to go.
BEWARE THOUGH: If you want to play online, you'll need a private header. Short explanation: Headers are a piece of code that Nintendo connects to a physical cartridge. It's unique for every cartridge. Nintendo checks this header if you're playing online. It checks if you're the only one with that piece of code online, because ofcourse only ONE physical cartridge is able to play online. Alas, one physical cartridge can't be in two different 3DS' at the same time. Get it? If there are multiple devices with the same piece of code, you'll risk a ban. A private header is a piece of code only you have. You can either buy it (beware of resellers though. They can sell the same thing multiple times) or extract one from a physical cartridge you own using Power Saves. I hope it's a little bit clearer now. Ofcourse, if you never plan on playing online, you don't need to worry about private headers and can just use public headers