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 > Languages and input > Manage input methods > US Mac Option Keyboard. Then, go back to Languages and input and select US Mac Option Keyboard to enable it.