You can’t govern an IT/OT estate you can’t see
An inventory says something exists. Governance needs more than that. You need to know what it does, where it sits, who owns it, what it depends on, who supports it, whether it is still required, how important it is to the operation, and what its security context is. A count of assets does not tell you what to do.
The useful question is not how many assets you have. It is which decisions you can now make. Lifecycle investment, cyber remediation, site standardisation, migration planning, supplier ownership, software rationalisation, criticality and support coverage all depend on that context. Discovery that cannot be used for one of those decisions is still only a list.
IT and OT are not discovered the same way. Corporate IT can often be found by automated tools. OT needs more care: operational availability, legacy systems, the shape of the network, and the method used to look. A scan that is routine on a laptop estate can be the wrong method on a site that has to keep running.
If the work ends as a spreadsheet nobody maintains, you have a snapshot, not a capability. The objective is not simply to find technology. It is to understand enough about the environment to make better decisions about what happens next.