With the additional information, I have some general recommendations.
0) Don't over-think it.
1) Don't be quick to Jump to GAMP 5 for a commercially available piece of test & measurement equipment that is going to be used as a general tool for it's (marketed) purpose.
I don't want to poo-poo GAMP 5 (I was once a dues-paying a member of ISPE) but (a) it is expensive to own a legal copy of GAMP 5, and (b) if you don't own a legal copy (it's got a LOT of details and information in it) you are probably working with some watered-down version that you cannot trust is actually implementing GAMP 5. Most NPS process implementations I've seen that are "inspired by GAMP 5" have sharp edges/dark corners that (ironically?) get needlessly complicated for folks who haven't really engaged with the publication (and supplementary materials from ISPE) directly. I am aware that GAMP 5 is intended to be scalable (beyond the inherent scalability of suggested activities based on the nature of the NPS system) but I would never claim to be an old testament scholar just because I get a few select readings and a poem on Sunday mornings.
2) There are elements of this NPS that you will have to consider, even though I am going to go in a different direction.
What you are faced with is a measurement tool, so the primary concerns are about capability and reliability of the system (men, machines, methods) for the appropriate materials. Since it is a piece of equipment, you should have an Installation Qualification that documents all the important elements of the system, including the software version provided by the vendor. After identifying the nature of the objects to be measured/tested, you should (internally) generate confidence through appropriate means that the system is behaving with an acceptable range of outcomes... it could be gage R&R, round-robin challenges, whatever.... just like any other measurement system.
Now the thing you will have to keep an eye on, even if the system meets your needs: The manufacturer may find bugs or offer software updates. You ought to have a mechanism to stay aware of these. In the GAMP 5 approach, this is a lifecycle activity.