croc
https://github.com/schollz/croc
Send files over the internet.
It's a small (several MB) CLI tool, that you download and run on both devices (sending and receiving one)
Type croc send [file(s)-or-folder] , you get the code phrase that you send to the person receiving the file.
On receiving device you type croc code-phrase and the file starts transferring.
End-to-end encrypted, and no need for port forwarding since it's sent over the relay (you can even host your own relay).