Hmm ... I like your question. But more detail seems to be needed. For example, you want to launch matter into low orbit. Then you take a booster rocket to lift 1 kg to that height. And scale it according to the decrease in load. But, most likely, the difference in the lift of 1 kg and 1 g will be too small for the weight of the rocket to be significantly reduced. There is a Skylark Nano rocket for lifting up to 1 kg. Take a look. It is only 2 m high. It is hardly advisable to build something smaller. At least with current technology. Perhaps when we'll find a fundamentally different source of energy for rockets, then talking about a further reduction in size will make sense
Yes, about a year ago, here was a splash about sending a tiny probe to the Centauri system using a sail and powerful lasers. It's believed they could achieve up to 20% the speed of light, so at that speed, the time would only take about 21 years, though it would be fly-by event.