At first, text only, for the proof of concept. But could be extended for files.
How do you solve it now?
Discussion
I either upload the file to a cloud provider (Dropbox) or email the file to myself
I highly recommend trying syncthing, that is the best for sharing across devices.
1. Install syncthing on your devices.
2. Share a common folder across all.
3. Anything you put in the folder will be synced.
Also works with sharing notes across devices! I used it with obsidian.
One caveat: Both device has to be online for the sharing to work. But just sharing files, this is always met.