thanks @ogra I did have some issues re SSL and setDevicePermissionHandler. both resolved now. I can package electron and run locally (on a mac) and all works correctly.
however when I run as snap I now see the following apparmor error
AVC apparmor="DENIED" operation="open" profile="snap.electron-kiosk-wayland.electron-kiosk-wayland" name="/sys/devices/platform/2300000.pci/pci0000:00/0000:00:0a.0/vendor" pid=3016 comm="electron-quick-" requested_mask="r" denied_mask="r" fsuid=0 ouid=0
I noticed your other comment here Raw-usb access to /sys/devices/platform/usb** re hardware-observe. From my snap connections output above it looks like hardware-observe is already connected.
I did try snap connect electron-kiosk-wayland:hardware-observe it made no difference
any other advice?