Hell yeah, this series is one of my favorite FGO derivatives
Idk if we will ever get an Achilles chapter, but this is relevant enough. Fun fact about Patroclus and Achilles, most pieces of classical greek literature depict them as lovers. Patroclus often has a beard, while Achilles is clean shaven. Extrapolating from that, we can interpret Patroclus as the older/mentor, and Achilles as the younger/mentee. By greek mentorship dynamics, we can deduce that Achilles was most likely a bottom. Think about that whenever he debuts in NA
Don't be cowards, FGO writing team. This is the not so deep lore you can find by googling Achilles.