Stumbled across this on Asus zentalk forums
https://24by7everything.blogspot.com/2020/03/asus-zenfone-max-pro-m1-march-2020.html?m=1
Disclaimer: no affiliation with the blog, just helping
You're right, unofficial unlock involves using the fastboot commands script and OTA still works that way. Search and try different recovery versions to see if they fit your need.