If the ADA does not address ESAs, then it's clearly entirely dependent upon whether or not there are provisions in state law.
If there were federal regulations for ESAs and a different state law or no state law, one might appeal to the HRC (Human Rights Commission).
Otherwise, without federal regulation for ESAs, it clearly falls to state law.
If there is no state law for ESAs, beware.
Many people get confused. Laws/regulations for Service Animals do not apply to ESAs. Any provision must specify ESA.

WC