The hardware might be fine. With the software, it's already harder, it needs adaptation, if not writing from scratch. With sensors, it's fitting them to the unique mechanical circumstances of the one-off machine. And both if these you can't scale, can't reuse.

For that specific customer, off the self stuff would not last more than a day or two as it had to survive -20C to 80C temperature swings in the space of a few minutes, along with the enclosure being rated to IP69K. The single board computer we used was off the shelf, then modified to survive the conditions inside the enclosure (eg: adding conformal coatings).

Making electronics survive those conditions is expensive and most people don't need that level of protection.

A PSoC-focused design trades flexibility for price, power, and performance. Hard sell.