Overhaul merging Krastorio2 with Space Age.
Large total conversion mods.
Transportation of the player, be it vehicles or teleporters.
Augmented or new ways of transporting materials - belts, inserters, pipes!
Trains are great, but what if they could do even more?
New ways to deal with enemies, be it attack or defense.
New Ores and resources as well as machines.
Things related to oil and other fluids.
Related to roboports and logistic robots.
Furnaces, assembling machines, production chains.
Changes to power production and distribution.
More than just chests.
For fertilizer,It may become a choice for who don't like matter tech polluted their pentapod hunting ground.
You could just import from Nauvis. Assuming your science is there you're delivering Agri Cards from Gleba to Nauvis so you can bring them back on the same ship.