I stuck the term "hand engraving Canada" into Google images search and came up with a whackload of pretty good engravers. Far more than I would have expected, truly. A lot more pictures of gun parts than you would have thought, too!
Worth remembering that only the receiver is "the firearm", so you can legally send pretty much any other part to any engraver that is willing to talk to you. The engraver that does the serialized component, will need the appropriate paperwork for the type of firearm otherwise, which may or may not limit things.
Cheers
Trev