SAJ.
Those big end shells look OK in as far as there no deep scuffs or gouges, but appearances can be deceptive. The only way to be certain is to assemble the bearings and measure the clearances between shells and journals. A product called Plastiguage can do that. You would need to find out the maximum recommended clearance from Audi.
https://plastigauge.co.uk/
The uneven wear is because most of the load on the shells is vertical. There is little horizontal load hence the sides don't wear as much as the tops and bottoms.
I can not be certain from a couple of photos, but from the evidence you have presented I think it is unlikely the big end bearings are the cause of the low oil pressure. If they were badly worn the engine would be noisy with a distinctive "big end knock", however having gone to all the effort of removing the sump and big end caps it would be worth going that little bit further to measure the clearances, otherwise there will always be that doubt in your mind.