You're looking for a game that blends the simulation depth of The Oregon Trail with a pioneering theme, but without the virtual family or Sims-style gameplay. Finding a perfect match on the iPod—especially older models—can be challenging due to hardware and software limitations.
While not exact replicas, these titles offer similar experiences:
If you have access to an iPhone, iPad, or computer, you'll find a much broader selection of deep simulation games with pioneering themes, including modern ports of The Oregon Trail itself.
The iPod's constraints may require compromises, but enjoyable games with a similar spirit are still available. Check the App Store for the titles above, or consider playing on a more capable device for the full experience.