I'm a non-native English speaker and I used to struggle as a teenager to read e.g. Harry Potter in English with a dictionary by my side. Literature is full of words you will never encounter in a casual or professional setting and that ESL learners won't know from having been schooled in English lit. So some way to quickly open en.wiktionary.org for a given word or some option have that in a tooltip on hover or when pressing a special key could be helpful, but I'm just guessing.

Very neat website, and very well made, congrats!