Flashing a USB device with Chromium on Linux

I recently gave in to peer pressure↗ and ordered the adorable little Xteink X4 ereader↗. It came in yesterday, and I immediately set to work flashing the recommended open-source community-maintained firmware, Crosspoint↗. They provide a handy-dandy web-based flashing utility to make it nice and easy... but of course it didn't work for me right off the bat. It's a wrinkle that I've had to iron out several times in the past - basically any time that I switch operating systems on my laptop. Most recently, I impulsively decided↗ to switch from the stable Bluefin release to the Dakotaraptor "distroless" alpha↗. I knew that the WebSerial API was only available on Chromium-based browsers, but even using the right browser the utility yielded an error about Failed to execute 'open' on 'ttyACM0': Failed to open serial port. The solution was to find out which group owned that port: $ ls -l /dev/ttyACM0 crw-rw---- 166,0 root dialout 19 May 08:09 /dev/ttyACM0 And then make myself a member of that…