I'm running it on an M1 Mac, Ventura 13.0.1.

Opening the game just shows me what seems to be a loading screen with some rectangles on the lower right corner, but the game doesn't start no matter how long I wait. I've tried installing it both with GOG galaxy and using the offline backup game installer, but neither worked.

I tried going to the GOG Support Center to get support, but I can't even select my operating system in the chat with the bot.

Not all Mac games are compatible with M1's architecture.
I just bought the game and also own M1 mac, had the same issue.

Try running it with Rosetta:
1. Find "NORCO" in your Applications folder
2. Right click the app and select "Get Info"
3. Check the "Open using Rosetta" box
4. Close the window and run the app again.