I did try this yesterday with my phone's hotspot but it was still failing, however I re-tested it today with a friend and they are able to see the server after adding it to their "Favorites" as my <public IP>:27015
It seems that might have been my problem all along. I misunderstood how steam server list works. It seems it provides the list to your client at which point your client checks if it can communicate to those servers. Since I couldn't connect to my own public IP it never showed my server for me. I can see my own server from another IP or using VPN.
SEOS keywords below, please ignore
Steam ARK steamcmd unofficial session not showing up, LAN works, friends can't see ARK server, port 27015, port 7777, can't see server but LAN works, portforwad but server not showing on listing, dedicated ark server not showing on listing