Building on someone else's platform is always gonna be a risky move, and building a platform on top of someone else's platform is even riskier.

My company used to use a hosting provider that was basically AWS plus some extra guarantees. We just finished migrating onto regular AWS because they now offer what we need directly.

But...AWS is a platform too, no? Seems like you're in the same category of risk you just moved to a more well-known name. Granted, Amazon is the most reliable even if they have their own quirks.