How to integrate with Ondc?

Can anyone tell me what is the criteria for converting an existing online store into ONDC integrated buyer app? Do we need to do extensive paperwork to get the approval (since it’s govt backed protocol)? And is it as simple as just integrating their APIs to pull catalogue & inventory levels, then push order data back into Ondc or do we need to run any integration layer/store all sorts of data for compliance? Any heads up from people familiar with the protocol is appreciated.