Take a look at Star Trek ( or anything like that ). It’s exactly like being in a building, except when you look out the window, then you get to see that ‘star smeer’ if you’re travelling at warp, or just stars ( that aren’t moving ), if travelling at sub-light.
You could just put a sky sphere out there with a cosmos on it and rotate it very slowly, I think that’s all you need.
Here’s my fake spaceship window
All it is, is a sphere ( material on the inside ), with a starry sky material on it. I’m rotating it using the level BP
and I’m standing next to a thing that looks like a spaceship window:
