@Max8 Unfortunately since Public Mobile has no roaming options besides the USA you're out of luck until you return to Canada. If you still have the old phone with WhatsApp you will have to use that phone for it.
You can consider downloading TEXTNOW APP on the new phone. You'll get another Canadian number in your area. It allows you to make free calls and text to Canada/USA numbers over WiFi (or data) anywhere in the world you are. Has caller ID and even voicemail if you're not online. Other people do not need the app.
The only other option you can consider to get your apps working on your new phone is if you have a family member/friend in Canada that you trust. You can have them go out and buy a brand new Public Mobile sim card from like a Walmart or London Drugs. Once they have the new sim card get the sim number from them. Log into your account and click change sim card. You'll be able to authorize the change via an email they send you. Once you've changed the sim card number on your account then all your account and number will be on the new sim. Have them put it into a phone and then you can do your WhatsApp. The verification code will be sent to that phone on the new sim card and then they can just give you the code to type into your new phone in Europe.
Safe Travels!
