you’re wrong.
No I am not... I got this. And any good developer will tell you the same. There is absolutely nothing that cannot be done personally in-house without any 3rd party controls or services required.
But these 3rd parties try to misrepresent the truth and claim it cannot be done without them. Absolutely false and fraudulent. You can personally serve up apps that facilitate any device with no problem at all. There is no need at all for their manipulation nonsense.