One time link to open gate via HA

Hi guys, I have a rural gate on our property controlled via an ESP connected to HA, its not a security gate or anything just a simple stop animals escaping. What Im trying to achieve with little luck is to send friends / family a link via SMS or Email which they can click on to open the gate on arrival. I dont really want to run a webserver on the ESP and expose that to the internet. So wondering if there is a module in HA that can provide a interface to achieve this, I have cloudflare with their reverse proxy in place. Any ideas or thoughts?

Without having them authenticate to Home Assistant, the closest I see is having a custom web service generate the one-time pass and calling Home Assistant to open the door when a GET request containing the pass is received.