I agree with most of the above. Generally only things that would support immediate needs are kept with the gun.
Firing pin, FP spring, slide stop, recoil spring.....

I didn't see a spare firing pin stop mentioned yet. I keep one of those. If the FP spring gave up, the firing pin stop can get lost easily.

Do you have a pin punch in the kit?

Oil?

I keep other spare parts in storage.