Hi,
Had a quick search around and found this information at the public mobile website to check/setup APN:
https://apn.how/ca/public-mobile/apple-iphone-8
These are the APN settings for an iPhone 8 on public mobile.
Also here:
https://www.publicmobile.ca/en/qc/get-help/articles/set-up-data-on-an-iphone
You can either use the search field or scroll down to one of the topics or click on support link.
Hope this helps