I cannot claim first-hand experience with AMZ Retailers or recommend it as verified. Before outsourcing everything, split the workload into inventory, fulfillment, support and marketing, and identify the most expensive bottleneck.
Ask a potential provider to demonstrate a real workflow: an order arrives, stock changes, fulfillment fails, a customer requests a return, and the issue reaches a person. The exception handling matters as much as the automation demo.
Keep ownership of your Shopify store, ad accounts, domains and customer data. Use appropriate staff or collaborator access rather than sharing the owner's password. Define permissions, response times, reporting, fees and an exit/handover process.
Start with one reversible, low-risk workflow and a small pilot. Measure hours saved, error rate and customer experience before expanding access. Shopify Flow may cover some routine store workflows, while a specialist team can address the gaps. Which task is currently costing you the most time each week?
J