The two key options "Non-US #" and "Non-US " are not available when remapping the built-in keyboards on System76 laptops running the open EC firmware. A customer (who is trying to configure his lemp10 to work with a German keyboard layout) described the issue and I was able to confirm on an oryp6.

Since our laptops only ship with US keyboard layouts and we do have a lot of European customers, this seems like it could be very helpful to enable on the EC laptops, if possible. I'm unsure if this would require an update to the EC firmware or not.

Screenshot from an oryp6: