The files are saved to $HOME/downloads/, after which the user
may choose to open the downloads/ folder or edit the file with
the $HOME/bin/termux-file-editor program.
It's also possible to receive URL:s, in which case the
$HOME/bin/termux-url-opener program will be called.
Starting with Android 6.0 the system may automatically backup app
data when a users installs an app on a new device or reinstalls an
app on one. After this commit this only affects the $HOME/backup/
folder, so that the user may choose what to backup.
See https://developer.android.com/training/backup/autosyncapi.html