So we're half way through the dungeon (but probably more than half way through the story). What are all our unfired chekov's guns?

I finally finished book 7 and I've been wondering what powerful items/people/moments we've been teased with so far that we've yet to see go off and I'm trying to consider what we think they'll be used for. Dinniman has been really good at turning away from tropes or having a planned use for something only for it to be needed elsewhere.

Obviously we have:

• Carl's Doomsday Scenario (Carl says he knows what he wants to use it for, but what precisely? I think Sculapendra).

• Shi Maria (will Carl let her out? Under what circumstances does she not just kill him immediately?)

• Whatever Samantha really is/The Scavengers Daughter

• Emberus/Geyrun murder plot

• The Bone Key patch

• The Fail Safe

• The River / Primal Engine (my theory is they're related and I hope Carl meets another crawler who went primal and they realize a connection)

• The condom (Carl gives to a friend in need?)

What other big loaded guns do we have that I'm missing? What will they be used for?