[pereb27]

1/ You can't sign homebrew for 3.56+ because we can't calculate the private keys for that.

2/ lv0.2 public (not private, once again cannot calculate those and therefore cannot resign) are mostly in bootldr (to be more exact, the bootldr revisions found on consoles that rely on lv0.2, so you can't get lv0.2 keys by dumping bootldr from a CFW console.