You may be surprised but a private (self-hosted) torrent tracker is how I did this when I had crappy internet and had to send over a bunch of pictures and video to family.

You can encrypt the data before sending, although it still should be fairly safe, speeds don’t matter much, there’s no storage to pay for or risk leaking.

Remember you can sometimes buy those games on GOG or itch.io too, and more money goes to the devs.

ORB: Off-World Resource Base is currently deeply discounted on GOG.