I lived on the Canada border in NY for a while…. I knew plenty of people who had pipes freeze due to power outages, poor insulation on new houses or after work on existing houses, etc.
Copper is easy and the tools to install it are cheap. Since the rest of your house is copper I wouldn’t worry about freezing unless the new plumbing is in an exterior wall.
If you need long runs pex is really easy too, but the tools can get $$$ depending on which type of pex you use. You can mix pex and copper also, use pex for the long runs and copper at each end.