"Annual percentage yield" is a creation of the TIS Act--a law covering nothing but deposit contracts with consumers. Accordingly, the term has no legal meaning outside that context. It's hard to see how you can shoot yourself in the foot by providing an APY, accurately calculated or otherwise, to an entity that is not entitled to receive one. Presented as a disclosure, it's extraneous information--so unless you somehow elevate it to an enforceable part of the deposit contract with the business entity, it's meaningless.
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...gone fishing.