The Handling Bundled SKUs in the Inventory section in the documentation talks about how the backend processing is done for a SKU bundle.
With respect to pricing, if you have an OOTB setup, then you could also try and create a SKU per the instructions provided in the Merchandising Guide for Business Users document to see how it behaves in OOTB Commerce Reference Store (CRS). Going by the fact that the BCC does not have a price section for a SKU Link, and that the sku-link item descriptor on the ProductCatalog does not have pricing related properties, I suspect that it maybe the price all of the SKUs that make up the bundle.
The Creating SKU Bundles section in the CRS guide describes how this is implemented in OOTB CRS as well.
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