Unlikely to be straightforward on Roku device in Canada.
BBC World is available in various ways, but not BBC UK (TV) news.
Apparently BBC sounds app is available on many platforms incl. Roku, try listening to news on Radio 4 (live or catchup e.g. Today programme) or World Service using that app. In many ways more succinct and informative.
For more information, you'd want to contact any specific channel/service provider to inquire further about whether they offer their channel/service on the Roku platform. Many channels on Roku are developed and maintained by the channel provider themselves. If you have any other questions or concerns, please let us know.