First of all, the dataset that you provided is not ideal for reporting, this needs to be unpivoted first. That will solve your problem of dealing with varying no. of Vendors by having a Fixed Metadata. This needs to be done before importing the data into Quicksight.
As far as the reporting is concerned, you need to find the minimum value at every item level. Level Aware Aggregation can help you with that. Once that is achieved that newly created column can be compared against the original column to create an indicator column which can be leveraged to keep the relevant rows which will provide you the right details. Please see the snapshot below for your reference. Hope this helps. In case this solves your query, please mark this as the Answer. Thank you!
