As I have mentioned before, I never ever had a patient ask for an ESA letter, but I did have a friend ask me to write a letter for her. That was really awkward, and inappropriate for her to ask me to do something unethical. Sorry- no.
I hope (but it won’t happen) that people can no longer purchase fake “service dog” vests for their pets. True service animals are very well trained and well behaved. Many pets are not. I have a friend who bought a fake vest for his puppy that he travelled with on an airplane. Puppies are not service dogs.