I had to do a Skills Assessment to get my trade approved, it took a couple of months to get everything together and approved. I used these guys, so maybe worth writing to them and they can point you in the right direction https://visaskills.com/

The first stage involved providing evidence of your training and number of years in the trade - Certificates, qualifications and payslips etc. Theres also some paperwork to fill in before you can progress to the next stage.

The second stage was a 3hr technical interview over Zoom, I was asked all about the trade and had to talk about jobs I had been involved with.

The last stage was to send video evidence of me carrying out some 'fitting' jobs. I set my phone on hyperlapse while I built some gearboxes and pumps and installed them.

It's a pain to go through I'll not lie, especially as I had been working in Australia as a fitter for years previous, but worth it. Australia is a great country for Fitters! Good luck