Yes, this is a farm based on that one by Ilmango but a bit smaller. Like I say, I'm not drowning zombies. I *am* getting nautilus shells so what is in their hands appears to be being harvested but no tridents so far. I was using a looting 3 sword when I got the trident I have but by my understanding, that only increases the odds a little. Ilmango's farm does have you kill the drowned yourself though.
I may try setting up a farm on a different server so I don't affect others with afk.