Option-a gives me å.
Not sure if that is specific for my keyboard or keyboards settings or language settings (all non-Norwegian), but I don’t think so. [MacBook Pro]
The Keyboard Viewer allows showing these key combinations, from being dynamic to the modifier keys, like a cheat sheet before you know the important ones by heart.
(This doesn’t show fully for extended combinations, like {option-e, then e, to give é} or {option-u, then u, to give ü}. But that’s a different learning curve. It gives hints with the orange outlines though.)