I remember that there was a plan for mega projects to be built. Are these still being planned to be put into the game?
Yes, but this will likely be near the end of development as there are a lot of more important features to implement for the moment.
I demand that there be a mega project called the Cabbage Differential Machine that through the power of MATH!, this cog and cabbage powered computer can increase the output of all workshops.
That's so brilliant that if devs don't include it in the game I'll make a catapult from half of their corpses to catapult the other half into the horrific cosmos and appease the dark lords. Or make some snarky remarks, whatever I feel like it when the day comes.