I think you could create an additional dataset which contains the list of file names that you have generated, and index these names in a “File” Object Type.
Then in workshop, you would have a loop layout, looping over this list of File objects. And the looped module would contain a simple button with a URL variable (and any other widgets to display eventual metadata that your File object contains). And the URL would be for instance:
https://FOUNDRY_STACK/foundry-data-proxy/api/web/dataproxy/datasets/ri.foundry.main.dataset.1b62272f-a231-4acb-90bf-3857c043336a/views/master/<MY_FILE_NAME>.xlsx
And the button would thus trigger the download of your xlsx file.
(This endpoint is not documented and might therefore be subject to change)