Porsche is different from most other OEMs in the extent to which they consider the tyre as art of the overall tyre/vehicle system. This of course makes sense from an engineering standpoint, but it is a cost that most OEMs will not undertake.
In Porsche's case I suspect that this is probably a result of having such a strong background in rear engine vehicles and their associated inherent handling characteristics (rear weight bias, high polar moment of inertia, etc) that can lead to on the limit difficulties for untrained drivers - the tyres can help in the overall management of such issues. (For the record these characteristics are not all undesirable - but in experienced hands I suggest).
However it is not just about "turn in" and other handling characteristics, although finding out you have an issue when you make a sudden swerve to avoid an accident for example is not really the time to learn, as witnessed by MacWhte.
It is also, for example, about noise in the vehicle. One example of that I have experienced in Macan is on road surfaces with a large aggregate in the bitumen - this can lead to quite unbearable resonances in the vehicle - and in that particular case the Macan was quite undriveable as a result. Because this particular effect is not a tyre thing, but rather a tyre/vehicle interaction issue, there is no way of knowing before trying the tyres on that road surface. There may be no issue on one vehicle (even another Porsche model) but a major one on another.
Tyre testing is a very complex issue and testing is very time and resource intensive - as a result it leaves the consumer (and tyre dealers) with few good sources of independent information.
The tyre dealer is assumed by most consumers to have such knowledge and they feel they should, so will give an answer to most queries to get a sale and/or to try and help, but they only know from customer feedback (not reliable as not trained testers) or the tyre manufacturers (the main brands such a Goodyear, Bridgestone, Michelin, Dunlop, etc will generally know but they are hardly independent and do not provide info that does not show their product in the best light....of course!).
So where do you go? These forums and others are full of tyre advice and perceptions, but again from people genuinely trying to help but with no real knowledge, as they do not have the resources, knowledge or ability to undertake the required testing - regardless of how strongly they may present their views.
I have done these things at a very high level in numerous countries, trained many test drivers and tested with too many vehicles and tyre brands and types to mention and with most global OEMs. I have also actually designed tyres........and yet I cannot tell you with certainty what tyres will work on a Macan (or any car) trouble free without putting them on and actually testing under controlled conditions.
Just for the record, I have no association with Porsche or with any of the homologated tyre brands. Similarly Porsche makes no $ out of tyre recommendations per se (the Porsche dealer will though of course), its interest is making sure that Porsche customers have a great experience........so you buy another one!
So my advice is that unless you love to gamble, don't waste your time and $ - just get the best deal you can on a Porsche Macan homologated tyre and get out and enjoy a great car safe in the knowledge that it is not going to bite you when you most need it.
Hope this helps.