As a minor, you have limited liability under Swiss law and are only allowed to enter into limited sales contracts. So you could buy something and if your parents don't agree, they can bring it back and the seller has to take it back at full price. It is a matter of reasonableness. It is reasonable to assume that an 8 year old gets enough pocket money to buy chewing gum or crisps but not to buy a Playstation. A 16 year old, on the other hand, can probably buy a laptop with his apprenticeship wages, but it is not reasonable to assume that he can buy a 4'000.- expensive gaming machine.

Thus, there are sellers who require the age of majority from a certain price segment onwards in order to solve this issue in advance.

If you really need a P30 Pro and it is only worth it because of the Sonos, I would recommend asking your parents.