Ok, but it's not easy, just as the OP said, and it's
extremely risky. If you forget to turn off your wifi, that's a perma-ban from all Nintendo online services.
It is an extremely locked down platform. Nintendo does not want you sideloading stuff onto it. Your OP didn't say it's impossible, they said it's hard, and they said it's locked down. Both things are true.
Nintendo is infamous for battling side-loading harder than anybody else. This has been a battle for ages, one I've been following since at least the DSPhat. And look through their history - a big reason they were so successful in the second resurgence of gaming (after the failure of the Atari era) is possibly because of how locked-down their platform was, how stringent their requirements were when it came to games. Game developers hated it because Nintendo would go so far as to control how many cartridges could be on a given store's shelves (stores hated it too, because money was being left on the table every time they sold out, which was almost always).
Long story short, just cause hackers keep winning the fight against Nintendo, doesn't mean their platforms aren't locked down.