LETS TALKING ABOUT HALLOWNEST FARMING!!!
Obviously Hallownest residents would be limited on what they can actually grow due to limited space and the lack of sunlight. Most likely the light you see in the game is probably a combination of holes leading up to the surface and plants that produce their own light. These plants would have to evolve to tolerate a lack of sunlight, constant moisture, and gain nutrients from everything. So, the native plants in Hallownest are perfectly suited for Hydroponic farming for wide scale food production.
The nutritional medium involved could come from naturally forming underwater lakes that are populated by various species of cave fish and other small vertebrates. Either that or recycling tiktik/crawlid dung from other farms to mix with water and having said roots filter the water. Either would work depending on location. The benefit from both scenarios is that any waste byproduct made can be reused as nutrients for plant based crops.
Yet another benefit is that the plants provide a natural filtration system and the water that eventually exists is mostly clean and would require not so much treatment compared to water just pulled out of the lake. At the very least, filtered water will pass another filtration system/heating element to make sure all microbes are dead. The waterways can be a way to take waste water from the city above and pipe it to another section to be recycled into feeding crops. However in game, we can see that this system has collapsed and stagnant water lead to the flukes being able to thrive.
As for Greenpath, most plant life there has adapted to very acidic conditions. Most plants from this area I figure would be mostly inedible save for the native species that already live there (the mosskin). However some of the leafy greens could be harvested and used as a type of dressing or garnish to add a bit of ‘zap’ to mostly boring dishes. Just don’t eat a whole lot at once or it can cause stomach problems.
Woody plants require a LOT so most likely the most you’ll see is bushes. Outright trees are not likely so most fruit would probably come from berries. The trees that probably exist are the direct result of the White Lady doing weird tree god things.
Most bugs had their own windowsill gardens. Only the nobles and the rich could afford to constantly buy fresh food. Regular bugs were happy to be able to go outside and get a nice fresh tomato instead of having to travel to a market and then get home to find that your tomato got squished.
There are various plants that can be considered stimulants or mildly hallucinogenic. I’m not too sure how a bug would smoke due to things such as book lungs and spiracles, so most likely these things are eaten as a form of edibles.
Trade with other sections of the Kingdom mean that some sections have a cash crop that many bugs in Hallownest would go nuts to get. Things such as Honey from the bees, Mushrooms from the Fungal Collective, hell, Deepnest may have ultra potent medicinal herbs that only grow in the deep dark. Transporting fresh fruit and vegetables would have been a logistical nightmare so most likely, trade was in refined preserved goods.
There are quite a few anti-bacterial and anti-parasite plants that grow and it became common to just regularly eat these. Usually a couple a day would do it and it would provide protection from some nematodes and intestinal parasites. Boosting your immune system and making your body hostile to invading bacteria is a big boon, so even carnivores would do this.
There is a lot more I can talk about and I can make other posts on these but this is my general thoughts on how food production would work in Hallownest. After the fall, unless there were seeds stored in a dry cool place, many species of artificially selected plants would go extinct. Or, grow completely out of control. The point is fixing up these places and figuring out how to feed a recovering kingdom would be an immense job to anyone trying to start up the kingdom again.
