Ash I have a bit of 10mm steel rod about 1m long with about a 100mm right angle bend on the hold down end and a wooden handle on the top.
To be honest I havent used it much, only on one whip snake here in my yard and a couple of browns down south most of the ones I have caught have been random finds while doing something else not out specifically looking for them.

On another note, goannas are probably harder to handle than most snakes and can be more aggressive and do some damage, just tail them and dont try to grab them around the neck as they will scratch the shit out of you lol.
Blue tonges and sleepies just a hand under thier belly, dragons , tail in one hand and the other under thier belly when they settle a bit.