So I hate to bring bad news but
1) with excel that is not a real option as trying to spin over rows and create analytics is not something that you will really do easily in Excel, but its definitely not something you can do as part of an Agent request. It's just too large of data.
2) you need to preaggrate your data, meaning you need to create the analytics outside and make them available to the Agent, versus trying to calculate them on the fly (as Excel is not meant for this)
3) Take your data somewhere else, anywhere else, Azure SQL, Dataverse, even SharePoint. All of these would allow you to run jobs against them that would create the data set you need to expose to people without expecting your agent to do it in real time.
You can always leverage Power BI and it can do all the work you want easily and while I still don't like Excel, you can even point it at an Excel file, it will import all the data and do the calculations.
Then you can use your Agent to talk to Power BI via an Agent or straight power automate flow to answer questions.
IMHO those are your only real/best options. Sure sure I could do it in fabric etc but that's too much for the fact you only have 20K rows, heck even if you had 250K rows.
If these suggestions help resolve your issue, Please consider Marking the answer as such and also maybe a like.
Thank you!
Sincerely, Michael Gernaey
