I need simple gadgets to upgrade Pods B & C, and I believe I'll need complex and elaborate ones to further upgrade them. I've gotten all the main endings, completed all quests except for three (9S's unit recon, and two others I haven't seen appear yet). Is there a place / boss enemy I can fight that has a good chance of finding them? Does the Item Drop chip help at all?
I, too, ended up needing simple gadgets to finish upgrading the Pods. I basically followed the farming route in this video:
Essentially, all you do is teleport to the access point near where you first started the game in the City Ruins. Run up the stairs to the 6th or 7th floor and there will be a harvest spot if you run out of the building wall and jump back in (circumvent the wall by going around it outside the building). If you have the chip that allows you to suck in nearby items, you can grab it through the wall. Simply rinse and repeat and you'll get 10 simple gadgets within an hour or so.