Multi-branch inventory with cross-branch transfer + reservation, Magento native?

Yes, Magento Multi-Source Inventory (MSI), native since 2.3.0, was built for exactly this.

Architecture: define each branch yard as a source (e.g. phoenix_yard, tucson_yard, albuquerque_yard). Define stocks per shopping experience (a single “Southwest” stock that aggregates Phoenix + Tucson + Albuquerque, or per-branch stocks if each yard has its own ecom view). Customer geo-routes to a stock; stock aggregates inventory from its sources; cart shows accurate per-branch availability.

Cross-branch transfer: customer adds 50 sheets of 5/8″ drywall; Phoenix has 30, Tucson has 40. The source-selection algorithm decides:

• Ship from Phoenix (30) + Tucson (20), split-shipment, two delivery dates. Common for urgent jobs.
• Transfer-then-ship, transfer 20 from Tucson to Phoenix overnight (yard-to-yard truck), then ship all 50 from Phoenix next day. Common when the customer needs single-truck delivery.
• Will-call at Tucson, customer drives to Tucson with their own trailer.

Reservation: when the customer adds 50 to cart, MSI reserves 50 across the relevant sources for 30 minutes (configurable). Prevents two customers from racing on the last truckload. On order placement, the reservation becomes a hold; on order ship, the hold becomes a deduction.

This entire flow is one of the reasons trade supply lands on Magento, Shopify can’t do split-shipment or cross-branch transfer cleanly at all.