The country code can indeed be a bit puzzling, especially with online wallets. For exchanges like Binance, it's generally the headquarters' country that matters. If you're unsure, you can use "Other" and provide additional context if needed.
Your approach of a single entry with "Other property outside of Canada" and "Cryptocurrency" sounds reasonable. Just make sure to keep detailed records in case you need to provide further information.
If you're heavily involved in crypto, you might consider exploring a crypto mixer tool. It can help enhance privacy and security in the crypto world.