Congrats on the launch! One of the founders of Permify is here. We love this approach and Google Zanzibar paper, as we're a taking pretty similar approach with Permify but as an Open-source product.[1]
As some mentioned there are legacy tools like AWS Cognito, which mostly focuses on authentication and simpler authorization use cases. But it's evident for us, that in order to solve these problems you have mentioned[2] we need a product which can cover more complex use cases and easier to start with.