Challenges right now feel like an idle game: You figure out how to make a module, then wait for the 600/1800 modules to be delivered (and maybe copy/paste your factory so the challenge is completed faster)

My suggestion to make this more interesting, make it more like shapez 1's puzzle DLC:

Special isolated Islands that are not connected to any other, where you have a limited amount of resource nodes, and a depot.
You must make the module on this island, and deliver it to the depot.
Then the silver/gold tiers are unlocked for a specific amount of "modules delivered per minute".

The challenge is now figuring out how to make the module, but also optimizing the production of said module with the space & resource nodes at your disposal to achieve a desired throughput.

I understand the game is meant to be chill, and I like that, but a challenge that is just waiting around isn't really a challenge.