> So, keep shipping a finite resource versus producing in situ? What if there's disruption in the logistics chain?

This point isn't obvious though. E.g. we'll likely be shipping them finite supplies of food. Supply chain disruption sucks but so is your MOXIE breaking down. MOXIE and 10 weeks of backup candles or 10,000 weeks of backup candles.

It's not obvious to me which is the cheaper / safer option.

We don't use them on subs all the time because subs don't have a lot of storage, and electrolysis is pretty easy to do.