Here's an outdated FBI for ya

It does however work on nand, like you requested. The only real drawback of the version is it can't remote install cias with up-to-date SSL links.
Make sure to reboot the system after installing it because NAND titles don't get the giftwrap treatment - you have to look for em. As far as this wearing out the NAND, I think those fears are unfounded. A single 1MB write isn't going to hurt anything, just don't get in the habit of installing 3ds games to NAND or installing/reinstalling system titles all the time (or especially DSiWare, which are natively NAND based, unlike 3ds mode stuff).
If you're wondering why I didn't give you the latest FBI version, well, it appears FBI won't compile any more with my latest dkP environment

Sorry about that.
If anyone who can do so, these are the 3 things you need to do to have NAND homebrew:
1. Chose "SystemApplication" on the .rsf
ex.
https://github.com/profi200/3DS-app-dev/blob/master/yeti3DS/app/build-cia.rsf#L15
2. Also on .rsf
UseOnSD: false
3. After compiling, put the .cia on 3ds sd somewhere, and in Godmode9, find the .cia and select "Encrypt in place"
Done.