NET USE F: \\localhost\foo /TCPPORT:1234
A traditional UNC path becomes "\??\Device\MUP\ComputerName\ShareName" as an NT Object Namespace path (Or "\\?\GLOBALROOT\Device\MUP\ComputerName\ShareName" as a file path)
If you change the port number or protocol, is that encoded somewhere in the native path?
Fun thing to do, you can use "7-Zip File Manager" to explore unusual styles of file paths. A path like "\\?\GLOBALROOT\Device\MUP\ComputerName\ShareName\" will work fine in 7-zip file manager, even though Windows Explorer (and File Dialogs) will reject such a path.
I found the announcement, but not how it works internally: https://techcommunity.microsoft.com/t5/storage-at-microsoft/...
Unfortunately it doesn't look like they are planning to support ports directly in UNC paths.