As far as I know, many known Shopify dropshipping Apps only sync the inventory for their already integrated suppliers, no custom suppliers based on sellers.
Oberlo only syncs the inventory of AliExpress.
ShopMaster has a lot more options. AliExpress, Banggood, CJDropshipping, eBay, Chinabrands, and GogoMall, the 6 suppliers' inventory can be monitored and synced by ShopMaster. So if you dropship from the 6 suppliers, you can use ShopMaster to auto-sync the inventory and price. Its monitor and sync frequency is every 24 hours.