Both aquaponics and aeroponics provide ways to grow plants without soil. Breeding insects or algae may provide nutrition with very small amounts of mass needing to be transported.
> nuclear reactors
Yes, these are a necessity but we've sent one to Antarctica before and we could send a more modern one to Mars.
> nuclear and other fuels
The good thing about nuclear fuel is that you need a very small amount of it to produce a lot of energy for a long time.
> machinery for every eventuality (including chip fabs)
Colonists by necessity must make do with less and that does mean a lower standard of living and higher mortality but you know what they do it anyways because some things are worth trading comfort and a decade or two of life for. English colonists didn't bring the entire industrial infrastructure with them to the New World. They brought what would fit on the boats and had to make do with what they could create from local resources or do without. They had the benefit of subsequent voyages but I don't think anyone here is imagining colonizing Mars or Antarctica with a single expedition.
> raw materials
Mars (and Antarctica for the most part) do lack anything biological in origin, no oil or wood or crops as feedstock for chemical reactions but there are always alternatives. We usually don't use those alternate sources here because they are too labour or energetically or materially expensive but when they are your only option price and effort become less of a concern.
> all the challenges are at least an order of magnitude harder
No one who is attempting to work towards this is doing it because it is easy. I remember there being a speech about that which ended up with some pretty spectacular results.