This is amazing. My single complaint is the font size, it's too small for 16 A5 pages, so it feels like 16 A4 pages instead.
Everything else is awesome! The concept and writing, the local focus and scope, the dungeon, it's wonderful. The dungeon map is among the best I've seen, and your art style is perfect, it's totally your own. Actually, the map could be a great addition for the Extra Resources zip file! I'd love to put an unlabeled version into a VTT for players to explore visually.
The NPCs are super distinctive and weird, yet also very relatable, which I love. The extraterrestrial nature of Zykom is strongly implied but not explicitly stated, which I also love. You preserve some mystery while allowing plenty of investigation and experimentation. Rontoc is a great standalone adventure and a great addition to a sandbox map. Hats off!