“Observable universe” means all the objects in the universe that we could, in principle, observe from Earth given that there has been enough time since the beginning of cosmic expansion for light to travel the distance between. So yes, those aliens who became sapient 10 years ago on a star 1000 ly away count, even though we couldn’t detect them in practice. Anything within 13.7 billion years or so is part of the Observable Universe.
“Observable universe” means all the objects in the universe that we could, in principle, observe from Earth given that there has been enough time since the beginning of cosmic expansion for light to travel the distance between. So yes, those aliens who became sapient 10 years ago on a star 1000 ly away count, even though we couldn’t detect them in practice. Anything within 13.7 billion years or so is part of the Observable Universe.