For medical devoces its the manufacturer, and it's notified body.
It's no different than for the origami manufacturer.
It's all covered in ISO 13485 (and another similar standard for the software portion if your product contains software). It's called the risk based approach. You define what's called essential performance or your device, things it must do or the patient or caregiver is harmed. You then do a FMEA to determine what failure modes exist, and what the result of each failure is. You then make sure you have mitigation in place for each of those situations. You then document that all, get it signed off internally, by the FDA, by your notified body, and by the test house (for 14485, FCC testing, etc). All that makes up the stack of documents that allows you to sell a medical product.
It's no different if it's a generic product or a new novel one, same process same standards.
For food machinery it's also thr FDA for things like design and materials, and it's the local health department for those items. It's a similar but different ISO standard you need to meet depending on the specific machinery.
