I'm building something similar, but as an Excel add-in instead of a standalone product.

In real use-cases, it seems that by far the hardest part is figuring out the right representation for a spreadsheet workbook and the right primitives for the agent to be able to navigate it adeptly and cost-effectively; structure is incredibly variable and the data just compresses rather poorly (values, formulas, formatting, charts, pivots, etc.).

Great stuff though, think we'll see a lot of movement in the space in the coming years!