Spy x Family does well to craft a convincing world living under the threat of future war despite a calming veneer in the peaceful present, but Project Apple is a lingering specter of a darker time in Ostania. The initiative is alluded to multiple times in the series and is most famously connected to the Forger family as the project that gave their dog Bond his powers. But in chapter #103, the idea is alluded to once more, prompting suspicions that Tatsuya Endo may use them for a grander story arc in Spy x Family, so Project Apple is a concept fans will want to reexamine.

https://screenrant.com/spyx-family-project-apple-bond-anya-mysteries/