I have always called this mood lonely exploration, or melancholic curiosity. It has liminal qualities in that you feel between encounters or between spaces of meaning.

It sounds bad but indeed, early NMS did feel kind of meaningless, which as you said had a certain poetic quality.

Melancholic curiosity, or loneley exploration, are two things I am trying to capture in games I make. There is a game called Infra that I highly recommend if you enjoy that mood, and city infrastructure.