Can i keep my games and saves?consider https://github.com/Plailect/Guide/wiki for setting up Luma3DS + arm9loaderhax. it's easier and quicker than it seems.
if you're using menuhax, you can quickly switch by putting "Luma3DS.dat" and pointing any boot manager to that instead of "rxTools/sys/code.bin" (same offset 0x12000). if you don't have a boot manager, put the "Luma3DS" folder from "3ds" to the "3ds" folder on your SD card. https://github.com/AuroraWright/Luma3DS/releases