Cool. It's probably the ancestor of the modern tomato or something. Perfect for authentic salsas!
I don't know about ancestor, but they are closely related. It's definitely great for making salsas. I make salsa verde with diced avocado using tomatillos a lot. It's great for some red sauces too. I'm a huge fan of Mexican food, so tomatillos are a must.
It sounds like siling labuyo has been getting some fruit development with only one plant flowering. This is my first year growing tomatillos, but everything I've read says you should have 2+ plants for cross pollination and good fruit development, so I don't know. My 2 plants have 6-7 little lanterns growing fruit right now. They seem to be very easy to grow so far. They grow very, very quickly.