Hi,
I am a longtime user of Lumix cameras. I have developed an ASCOM driver for Lumix interface over http and wifi. this works well (on ascom obviously) but also on Lunix i have worked with Marcus Meisner to include Lumix also on libgphoto2. We managed to get the HTTP/Wifi as well as the native USB tether mode working on Linux at the time. I have not followed up much since i am now on Nina but might be worthwhile checking that history.
might speed up your efforts.
Thanks