Some time ago there was a spate of engine failures attributed to loss of oil pressure in Quattro's when on steep gradients, I don't think it was really ever proven to be a contributing factor but the longitudinal layout in the B7 and the tfsi engine did seem to indicate lack of oil supply could occur on steep gradients if the oil level was very low.
There was a revised part that guys fitted that had a bypass suction hole that should the gauze become clogged oil could still be drawn into the system.
But that's assuming the gauze has become clogged to the point suction has been reduced to a very low point, hence why the relevance of the angle of the engine sometimes.
Anyway, unlikely to be that as you had done an oil change and levels were fine.
Given the high mileage, it may be more oil pump related as they do fail and the drive chain does and if there is a lack of evidence of it being replaced or upgraded it is a very possible cause.
Given the cam chain tensioner is hydraulic, if the oil pump fails or is similar then suction will cease and the cam chain will become loose with mechanical failures following soon after.
Also consequently all oil distribution around the engine will also cease, thus leading to a raft of mechanical issues.
without full inspection from a good garage, it would be difficult to give you a remote diagnosis to be honest so best get it looked at but don't run it.
So in summary.
The car has been running issue-free up until the following.
You performed an oil service, and all was ok.
Shortly after oil pressure, the light came on and the engine became very noisy etc.
The oil level is ok still.
Possible causes .
Oil pump or chain failure leading to oil starvation of engine.
Oil suction pipe gauze clogged with a lack of oil also leading to oil starvation, also very possible but given it was ok before the oil change, not likely to be the whole cause but maybe a factor all the same.
after the light illuminated what happened and how did the car run for the short time?
