“This is even clearer from today, as we have signed an agreement with OZ- with very different standards. So meat could come in from OZ, be made into sausages in the UK, and then go on to NI and possibly on to the EU via Eire, by the 'back open door'. It is all very simple.”
No, not as raw sausages, possibly as a cooked meat product, imported ingredients have to be declared and tarriff, if any applied to them, that is detailed in the “Withdrawl Agreement”.
Nothing to stop us consuming imports, importing Australian Meat to make pies to send to the EU is one example, there are many others