Please no. Phones go into tunnels, run out of battery, and go indoors where there's a poor signal or none at all. They make terribly unreliable servers. Not to mention how much faster this would chew up battery life. If you want to keep a spare phone plugged in all the time in your closet, connected to Wifi/Ethernet, and hack it to be a webserver, then go ahead. But webservers on mobile devices, being used in a mobil…
Personal websites are info only. Don't change that much. Google can and should cache results. Once synced, the website could be behind Cloudflare to avoid DDoS.
Maybe the value of running on your phone would be so people could see that your phone is up or something like that?