Yea pretty sure it's head gasket
Missing on one or more cylinders, water gone from coolant bottle, steaming from exhaust. Coolant light came on pretty quick. There's oil spray in engine bay around coolant bottle area too so guess that's got squeezed out the split.
Nothing there suggesting HG to me.
Its *very* rare for the fire rings to fail on Omega V6. In fact, all the genuine V6 HG failures are on MFL 3.0l, where coolant leaks to outside at the rear of passenger bank.
Now, its possible you have this mode of failure, and the coolant has sprayed/damaged DIS pack, but I think you need further diags first.
My beloved MV6 failed twice, both times diagnosed by making a special coolant cap with a tyre valve in (and lots of sealant), pressure it to around 6-8PSI, and watch where is pisses from.
In my case, no other symptoms beyond coolant loss (relatively moderate - topping up every other day or so, but gets progressively worse) and that sweet smell all the time. Occasional steam visible from passenger side of bonnet when sat in traffic. I know in MaxV6's case, the leak was more catastrophic, but no non-coolant related symptoms.