I've not been involved in such an engineering project before,...

I've not been involved in such an engineering project before, but I would expect that yes, this is how it is normally done.
At some point someone needs to write some documentation that can be given to someone else to replicate the commercial prototype multiple times.
Dismantling and rebuilding the commercial prototype will be required to
a) write that documentation
and
b) confirm that the documentation is correct and that the process is repeatable.