Comment 4 for bug 1780678

Tested with the Numworks calculator v0100, Ubuntu 19.10.

$ dpkg -l chromium-browser
...
ii chromium-browser 77.0.3865.120-0ubuntu1.19.10.1 amd64 Transitional package - chromium-browser -> chromium snap
$ snap changes
ID Status Spawn Ready Summary
36 Done today at 10:20 CET today at 10:20 CET Refresh "chromium" snap from "candidate/raw-usb-test" channel
$ snap interface raw-usb
name: raw-usb
summary: allows raw access to all USB devices
slots:
  - core
$ sudo snap connect chromium:raw-usb
error: snap "chromium" has no plug named "raw-usb"

And without this connect, chrome://device-log/ says 'operation not permitted',
as designed.

At this point, the workaround of using chromium without a snap wrapper seems no longer available. The snap system knows something about raw-usb, but the chromium snap from the raw-usb-test channel does not want to connect to it.

Let me know when you want further testing.