In base GearCity there is no way to limit sales/production on the country level. A work around that could become burdensome is to create a trim of your design for use only in country A. You then use the autoproduction production restriction system, assigning A Trim to the factory in Country A, and it's parent model and the other model to the factory in country B. Do not sell A Trim in country B.

In our upcoming free DLC, 2nd Gear, we've replaced the production system entirely, but if you decide to use the old production system, restrictions to custom districts, including at the country level, was added.

Thank you very much for responding
Seems like I really need this DLC. Does it work for the steam version?
Will try to get it working on the current system though for now.

Originally posted by Robin Banks:

Thank you very much for responding
Seems like I really need this DLC. Does it work for the steam version?
Will try to get it working on the current system though for now.

It is currently not released, but it will be distributed on all platforms that the game is sold on, including Steam.