Integrate QR or Barcodes into Excel for Ongoing Data Entry into a Single Row?

Let me respond solely on the question of whether "there’s a method that allows multiple scans—each representing a different datapoint—to populate and update a single row over time, rather than creating new rows for each scan?" and respond by saying that, IMHO, that would be a terrible solution even if possible.

Why? Because, based on experience as the director of a major corporation's database on one set of transactions -- checking in, checking out, moving things around, new locations, whatever -- you will want to be able to recreate history. Not always. But sometimes. And tracking current status by simply updating a single row--new location, new aisle, new shelf, whatever--totally eliminates the ability to track history, while not gaining anything.

Tracking changes in location, or whatever, by entering date (and, if such level of granularity is needed, time) allows you at any time to create a "snapshot" of where that equipment is or was at the designated point in time. And it can provide history when needed.

In short, you'd be far better off creating a transactional database recording each movement, each change of status or workflow, with a new row...and using that history of changes to get your snapshot of current OR past status on an ad hoc basis as needed.