Sure, you can add or replace the map package on a Zumo easily by purchasing and downloading one from the Garmin site.
However, keep in mind that the LM means lifetime updates, so even if it's a few bucks less, you're paying for a perpetual subscription to European map updates which it seems like you don't need or want. To get the same mapping in the US, you'd have to buy North America lifetime maps, which is $90, on top of the device cost.
Unless the hardware you're looking at is really $90 less than the comparable US unit - which I doubt, I wouldn't bother going this route.
2012 DL650 Shiro Nakama #27
Ride Report: https://www.stromtrooper.com/ride-reports-route-sheets/79121-footsteps-lewis-clark.html