I imported the Excel file as an object
It is more correct to say "I inserted an Excel workbook as an embedded object in a Visio document".
I need to import the Excel file in a way that allows me to search the table's data directly within Visio. Does anyone know if this is possible?
This is not possible through the Visio user interface, as it only searches among Visio objects. Excel in this case is an embedded (foreign) object.
But you can write bite of code to do it programmatically…