I'm guessing that in the countries that have such laws, nobody is going around and enforcing that people are working with external keyboards in their homes, but

I'm guessing that in the countries that have such laws, nobody is going around and enforcing that people are working with external keyboards in their homes, but instead, employers are probably required to provide this equipment if an employee must work from home. Among workers, I imagine such laws raise awareness of the risks of working for too many hours on a laptop keyboard. I wish I had such awareness before I developed bad RSI pain after working on a laptop too much during previous WFH stints. Now I'm much more careful about my home work setup.