Could people with Iron Age technology possibly dig large holes in volcanic rock on the edges of a lave tube system. Would this be an effective way to run a trade business or to live in an underground home. I know that Kazumura, the world's longest mapped lava tube, which stretches more than 40 miles and in places is the size of a subway tunnel, so size definitely isn’t a problem. The volcano would be extinct so there are no dangers regarding an eruption.
[Kazumura lava tube system] -https://youtu.be/8OYuWLVb1xI
i.e. : Would this be efficient, would this be possible, & has anything like it eve been done?