Can’t test as I am still on NC18, but what do you mean with upload from multiple locations?
Would for example an upload via multiple ISPs work?
I have a router with OpenWRT that through mwan is connected to more than one ISP the same time. But uploads and downloads usually only utilize one line at a time, but multiple parrallel ones are of course faster.
Also what about the same in reverse if I would host Nextcloud behind such a multi ISP setup?