In order to verify the status of the integration there you need to make sure that the setup is correct.
There are few steps to verify each stage of the integration: onboarding, catalog setup, order management and finance reconciliation.
There are two ways to onboard new partner: manual or via commerce manager redirect with OBO.
Specific check for each path are
There are three options how to work with catalog and inventory: scheduled feeds, Feed API and Batch API. Common check for all of them:
Finance payout endpoint is pulled regularly to see new payout information for the reconciliation.
In order to validate that merchant experience is correct, for a test account and first onboarded merchant follow the seller test checklist.