If you need to use a file sharing service, this site:
https://www.privacytools.io/software/file-sharing/ recommends a few
alternatives to wetransfer with good privacy practices. I don't know if they
are libre, but it's is worth to check them out:
https://send.firefox.com/
https://covid19.framadrop.org/en/
I stopped using wetransfer long time ago, because it refused to accept zip
files, which could easily be encrypted cross-platform.
Or maybe a free software community could collaborate together and create such
service using an open source code. I bet a lot of people here has some spare
space on their servers to host some files for a short period of time.
