> At most, the buyer would need to allow the financer access to retrieve their property. The financer could then sue the seller for the buy-out cost and/or breach of contract.

Nope, at least not typically.

Typically in the US houses are sold as-is unless it's noted in the closing docs. Everything in or on the house when you close is yours. The seller would be the one fighting with the financing company, as (again unless noted in closing docs) they would be considered fixtures and considered part of the real estate sale.