Today I played around a bit with a Meshtastic device and tried to configure it through the Web Serial API in Chrome.
On my Linux system it could see the device but not really change any values, update firmware etc.

This confused me for some time, until I looked at the permissions of /dev/ttyACM0 (which were crw-rw----).
A quick sudo chmod a+rw /dev/ttyACM0 later, and I could write to the configuration of the Meshtastic device.
The more tedious part was that after every config change the device rebooted and the USB serial connection was re-initialized by Linux, thus I needed to re-run the chmod command after every change. Luckily I figured out how to enable WiFi on the device and from then on no longer needed the serial access.