@JaredBusch so currently the file is pushed to a server placed at customers' sites?!
You can write some http API but still you need to set the server.
Can't you othetwise keep the sftp server at the source and let customer use any ftp client (even the browser) to download it? Basically this reverse the process snd customers pull the file.
Winscp offers scripting automation as well so you could send that to them to automate the download to whatever folder. I believe it offers some recording function as well if you don't want to manually script it.
SCP is part of Windows now by default. If your OS is up to date, or if you add it directly as a component, you don't need any third party tools. SSH/SFTP/SCP is there for CMD/PS to use and you can automate that way.
My point was the other side could generate what they needed to do in the GUI of WinSCP rather than having to script it if they didn't know how https://winscp.net/eng/docs/ui_generateurl#script