I was wondering if there's a way to trigger notification from Terminal or bash script on Chrome OS. Similar tools are already available on most other desktop operating systems.
hterm supports the OSC-777 sequence (from rxvt-unicode) for generating notifications: https://chromium.googlesource.com/apps/libapps/+/HEAD/hterm/doc/ControlSequences.md#OSC
An example script that you can use: https://chromium.googlesource.com/apps/libapps/+/HEAD/hterm/etc/hterm-notify.sh