DS mode can only be used if you actually boot up your console. Unlikely that we’ll ever see an equivalent to open_agb_firm. Your best bet is to use ndsForwarder to “install” DS titles right to your home screen so you don’t need to navigate Twilight Menu every time you want to play a game. You could also just get a flashcart, those are pretty speedy.

Infinity for Reddit. Slightly ugly but far faster and smoother and lighter than Reddit (even patched Reddit.)