Upload an Excel file with only validated rows.

I don't see how you can have a one step process without having a way for the uploaders  to deal with their rejects. 

My suggested solution could allow each separate  user to deal with their own rejects. 

My solution would be an upload and a button click. 

Also, It sounds like you would be using up a a lot of Step Runs if you are dealing with records one by one in pipelines.