I have found another more user friendly way.

I have installed the SFTP plugin into Total commander and I set up a connection using the other device's IP address (172.28.172.2). This way I can browse the other device like a local folder and copy/paste files from and to it easily.
What is interesting though with this solution, while TC on the host device cannot "see" outside of the android "box", the target device where I sftpd in shows everything, including the sailfish os root.

My next other idea is mounting the other device into a folder. (I am using the cifs package from openrepos for this to connect to my NAS at home when I need.) If this is required to run a samba server on the target device, for Android there is a free one in google play store that supports SMB and CIFS.) Plus there is the JuiceSSH app in there so the connection via ssh should also work on Android too.

I know this is not so universal as bluetooth but I think it is more secure as you only turn any of these on if and when you need, while a bluetooth can be left on. (Although a switched on bt might not be an issue, I don't know as am not good at hacking.)