Checking out Retool and in the resources Google Sheets is listed, but can we upload a csv file to the tool?
Hi @gbmaier and welcome to the forums! Yes, you can absolutely upload (and automatically parse, and do all sort of wonderful things) CSV files. Some documentation here for a basic use case.
Lots of other great use cases can be solved as well (augment the file and send it back to the user, validate the file, put it on a cloud storage site, as AI to summarize it, ask AI to rate the data in it...I could go on 
)!