Hours of re-installation, reading and a lot of frustration and it is just done with an one-line command ?!
dom0 : sudo qubesctl state.sls qvm.usb-keyboard
Kicked off sys-usb and … 2 sec of shocking moments … and then all USB devices are detected and now attachable to AppVM !
One reboot to see if LUKS will let me in and sys-usb will auto-start on boot