200 amp will do 8mm okay and more
Foot controls are over rated
For thick material though you will need a water cooled torch.
Unimigs used to be good welders but I don't know what they are like these days, hardly anybody makes there own welders anymore, most of them are rebadged to suit the seller.
Quality units are $5-6 grand
There are a lot of these style of units around between $1-2 grand
The old story; you get what you pay for.
Its the duty cycle that comes into it if your going to be welding all day long.
Have you TIG welded before?
If not then factor in a couple of bottles of argon and lost of scraps to get the hang of it.
Controlled melting, you have to develop judgements, not unlike buying a MX bike and then learning to ride
Same thing here but I know nothing of the seller
https://www.ewelders.com.au/uni-mig-tig-mma-200amp-ac-dc-inverter/