US Mac Option Keyboard
Enables the option for US Mac Option keyboard in Language Settings. With this keyboard layout, the right alt key (AltGr) behaves like the option key on a Mac keyboard, allowing special symbols to be typed.
To enable, install the extension, then go to Chrome OS Settings > Device > Keyboards and inputs > Input settings > +Add input methods > US Mac Option Keyboard > Add. Then, under Input methods, select US Mac Option Keyboard to enable it. You may now close the settings window.