I want to retexture the ice blocks in Minecraft Java Edition into roads that I can run around my town (with boats as cars) but I'm wondering whether I can orient them to have them facing E/W instead of N/S and vice versa. Is this possible?
You can look at a block with the debug screen open to check whether it has block states for rotation, only then it's possible. In some surprising cases it is, like floor buttons differing between North and South orientation, but ice does not have such block states. You would need a mod for server and client to change that. You could try to re-implement ice mechanics for a different block with a datapack, but it's unlikely to work well.