What about Synching? It seems to have the same use case
https://github.com/magic-wormhole/magic-wormhole
I don't know why this stuff is not installed by default in all PCs and phones.
Discussion
It seems best suited for synchronizing entire folders, possibly with a recurring strategy.
Magic Wormhole is great for one-time transfers, even from different parties, such as from a friend. Lately I've been using it to copy configuration files to a new (actually old) phone, since transferring via bluetooth didn't work and I didn't want to mess with usb cables or use a PC as a gateway.
Do both users need Magic Wormhole installed?
Yes.
Or maybe there is a web client (it's an open protocol) that can fetch the file without installing an app.
It exists: https://winden.app