All three countries are putting more resources into it. Sounds like a serious effort to me, even if the vast majority of busts and seizures are not fentanyl-related.
Joint Statement from Mexico, Canada, and the United States Reaffirming Our Shared Commitment to Address the Regional Challenge of Synthetic Drugs and Firearms Trafficking
But the vast majority of fentanyl and/production chemicals are coming from the Southern border. Mexico and precursor chemicals from China coming through Mexico are the main driver. The DEA even says that Mexico remains the dominant source of finished fentanyl products, while Canada plays a minor role, often involving small-scale smuggling across its border.
And for context, more than 90% of interdicted fentanyl is stopped at Ports of Entry (POEs) where cartels attempt to smuggle it primarily in vehicles driven by
U.S. citizens.