I've set up a fulfillment service through a private app. I want to use this service for inventory management. Currently, I'm having to push products into shopify individually to sync their inventory with our system in-house. However, using a fulfillment service allows me to sit back and wait for Shopify to ask my app what the stock level is for a certain SKU, perfect!
But I would like fulfillment_service to be 'manual' and inventory_management to be the handle of my app.
Also, when I change my fulfillment_service of my items, I lost the functionality to use In-Store Pickup in my app. Potentially this is a bug? Not sure why a fulfillment service would prevent in store pickup.