Yes ,and many Canadian homeowners do exactly that.
A properly insulated and sealed steel garage performs very well as a heated space. The keys are the right insulation system (spray foam is preferred for steel structures), a proper vapour barrier, and correctly sized heating equipment for your climate zone.
Spray foam insulation applied directly to the steel frame eliminates thermal bridging and condensation issues that plague poorly insulated metal buildings. Done right, a heated Metal Pro garage is comfortable year-round even in northern Alberta winters.