Is there a widely accepted definition of "Enterprise Platform"?

Not a platform definition, but perhaps the page for Enterprise Software is an approximation: https://en.m.wikipedia.org/wiki/Enterprise_software

For me Apple is a consumer device company.

I’m not talking about PowerPoint and Word-like services here, but CRM and BI services that S500 companies would also want to focus on.

MBP is not an Enterprise Product or service. It’s a consumer device that an Enterprise permits. Sales force, PowerBI, CRM, GSuite - those are Enterprise services. For example, I don’t see a FaceTime for Work or iMessage for Work product. They are first class consumer services as they should be.