The short answer: Canadian public documents are recognized in Ukraine through an apostille — since January 11, 2024 the Hague Apostille Convention applies between the two countries. Provincial documents go through the provincial authority (in Ontario, Official Documents Services); federal documents, such as RCMP certificates, go through Global Affairs Canada. The receiving Ukrainian side will also expect a certified translation into Ukrainian, and some institutions set their own freshness windows for certificates.
This situation usually means a fixed chain: the right issuing version of the document, the correct apostille authority, translation, and delivery. The routing question — provincial versus federal — is the step people most often get wrong, and an apostille from the wrong authority means starting over.