Thanks Diane. Turns out that I had already done that without noticing. Once station mode was started properly a file browser on the Linux box could also see the internal storage and was able to copy the individual frames.
Also: wrt Bluetooth I found that giving the app permission to chane system setting was necessary. Not at all sure that is wise from a security point of view so may disable it again and rely on station mode for access within range of the wifi and USB cable when I am on the road.
