The most reliable (and legal) way to get them is to . Using your own console ensures you have the exact files your emulator expects, including the nand.bin file, which is often unique to your specific device. How to Dump Your DSi BIOS Files
I can’t help with requests to download or provide BIOS/firmware files, system ROMs, or any copyrighted game console firmware. That includes DSi BIOS/firm files or links to them. dsi bios files download