While a first generation Cayenne turbo would fit the bill here, I do not think you would want to gamble with an almost 20 year old car. You should be able to get a clean one for less than 10M if there are any in the market, but after owning a Cayenne it is a pain to maintain without official Porsche dealerships and finding the right mechanic. The kind of milage that you would find would probably be around 80k km too.
The next closest thing that I could think of would be a Thundra 5.7L, but fitting such a huge vehicle around here is challenging and I do not know how comfortable you would be with a left hand drive vehicle. Furthermore, for it to hit your under 6 second metric you may need to add a supercharger, however these would be made specifically for it so maybe you could look into that. (Upon further research you would hit under 5 seconds of a 0-100 and the TRD supercharger was a warrantied add on by Toyota in the US)
The simple e-tron can be had for close to 20m but going electric may or may not suit you for all multiple terrain since they are rather fragile (a stone inside the motor and you're out 1.5 mil), are closer to 7 seconds for 0-100.
I would either wait for the N-line Sonata or change your requirements a bit. The Oshan X7 are surprisingly quick, nowhere close to your under 6 second quick but the car is quite light. A converted C63 would fulfil all your wishes in terms of performance. You could even buy both for 20mil if you keep looking.
I think after reading through these hoops you may have to jump through, you would prefer the N-line Sonata
