The short answer: An apartment in Ukraine can be sold while you stay in Canada. The sale closes before a Ukrainian notary, and your part is handled by a representative acting under a power of attorney — or, for some acts, by a power of attorney certified at a Ukrainian consulate. The main caveat: the power of attorney has to authorize the sale specifically, and the route for the proceeds deserves planning before the buyer is found.
In practice the sale splits into a Canadian side and a Ukrainian side. You prepare and sign a power of attorney where you live; your representative in Ukraine runs the viewings, signs the sale contract before a notary, and registers the ownership change. The money question — which account receives the price and how it later reaches Canada — is usually the piece owners think about last and banks ask about first.