They tend not to make them much smaller than the nano (I think that's about the current champ, though I'm an old traddie, and never chased the smallest/lightest bug TOO far). You'd get too small to handle full diameter (or even smaller 7 and 8MM) ropes safely.
A ss lock link might make sense for you, though it is not quite as cool nor convienient, though there are snap links out there. They will NOT be rated quite like climbing equipment, but will be stronger than cheap aluminum novelty biners.