Have the maintainer try opening the export with the account and tools they will actually use; a backup that only the departing integrator can open is more souvenir than handover.
Send the missing call name to the integrator while they are available, so they can provide that dependency rather than another copy of the main routine.
And ask them to demonstrate that the final export is complete from the maintainer's account, once the missing routine arrives; opening the archive alone will not establish that.