Two early cultures, 2 squads, an Expansion or two, both AW's, and the newer street type, plus some Settlement stuff not needed at all if one PP's certain productions this Chapter, are all optional.
I skipped the last Meditation Circle. The last Expansion can be done later.
Best however to do the two late Chapter optional AW's and the street, as they all demand lots of Portal output that can be spelled out quickly with PP's, but not done at all (or one of three can be if the Portal stuff is left behind) if one moves on and disables PP spells for that Chapter, or sells off Settlement buildings not as useful to build at all as in most earlier Chapters.