How type Euro on US keyboard

Shift-option-2

An easy way to find this sort of thing is Keyboard Viewer:

Use the Keyboard Viewer on Mac - Apple Support

For example, with Shift-Option pressed, you have these characters (and you can 'type' them by clicking right on the Keyboard Viewer):

Another simlpe way to type accent letters:

By holding the key, such as "a" "o" "c" ..etc, and Mac will give you the choices of European commonly used letters.

See below: