... but wouldn't it be at least 17x better if you could see a tiny render of your factory on the planet below?

can't implemented

I think it's technically possible, by taking a screenshot (or camera even) and rendering it on the planet, but there would be a few downsides.
- Factories would either be too tiny, too large or become too large, or constantly changing in size to fit on the planet.
- It would be hard to render the factory on the planet in a way that looks nice. I imagine it would always seem out of place when stamped on top.
- The performance impact of rendering the factory a second time would likely be very high.
- (And most importantly, I am not nearly a good enough modder to implement this correctly)

Theoretically possible, but very out of scope sadly.

It would also be entirely unrealistic. In reality, even the largest megabases would take up less than a pixel of space.

It would also be entirely unrealistic. In reality, even the largest megabases would take up less than a pixel of space. Perhaps an alternative would be to dynamically add small specks of lights and have more lights the larger your factory is, but again, kind of unnecessarily complex for such a small improvement

The only thing that could work to show some olanetary impact is visualizing the pollution cloud.

Take the image and add more and more smog to some region on the planet and change the background depending on the pollution rate on the planetp