I'm not sure I understand what you mean. Which things I listed are difficult to come by? With the exception of the SBCs/application-boards (which may need to be ordered like any other piece of hardware), the rest of it is just as downloadable and available as anything else used in the OP.

But, even if one concedes that the technology stack they chose was somehow the only one available to them, then what level of rigor should be applied to adapting a stack that would typically be considered unfit for this task under normal circumstances? I couldn't find any mention of their testing methodologies.

Knowledge/experience/expertise are not readily available. And I would find it hard to believe that a person would be able to churn out a piece of technology worth using, first try, with tools they've never used before. So in terms of your "hard to come by" question, I would say "A depth of experience at a moments notice" as a response.

"Crisis" seems to be a scenario that your methods might not work well in. Groups of people were at risk of death. Would implementing a solution increase their chances of death? If you're continuing to monitor patients as you normally would without this tech, isn't worst case just "doesn't improve"? And isn't best case "We caught more problems than we would by normal monitoring" ?

I can't really tell what you're advocating here. Using both unproven/unfit technologies and foregoing safety processes is worthwhile risk because the people doing it also lack the expertise to do otherwise?

The "worst case" that can come out of false positives & false negatives in safety-critical conditions has a bunch of dimensions depending on an enormous number of environmental and contextual conditions. There's no PFMEA nor DFMEA supplied in the OP to indicate how one should consider their choices.

Best of luck.