Btw, that document also explains that, despites tiles (on bg) are 8x8, you can only assign a palette to a 16x16 (a SMB block) or 32x32 meta-tile (a SMB pipe) ...

WRONG.

There's this MMC5 thing, which allows you extra RAM, which allows assigning palettes to 8x8 blocks. It also allows you some other things.