As someone who has been in the messaging industry for more than a decade, it sounds naive to think that the litmus test for whether Apple will ban you is whether your traffic qualifies as spam. There is a long history of people trying to get around A2P spam filters / fees / traffic limits / onboarding / KYB requirements by running business messaging on P2P pipes, like you are doing. Some of it has been successful (see Twilio in the early days) but the industry has gotten a lot more sophisticated around this stuff and is not going to be receptive to your approach, which to me resembles the SIM farms that are a scourge when it comes to consumer fraud and abuse.

++ this is going to get banned the moment anyone from Apple sees it