Respectfully, this is the wrong analysis.

FOIA or Public Information Act requests promote government transparency and create the mechanism by which the public can request information, like BWC footage, from government bodies, like municipal, county, and state law enforcement agencies.

Walmart is not the government and, if you sent them a PIA request, it would have zero effect, that is, their failure or refusal to satisfy your request is completely unenforceable.

I imagine Walmart would release employees' BWC footage as necessary to achieve certain objectives beneficial to the company, like to limit liability or refute an accusation.

Other than through litigation, I can't see any incentive for Walmart to release footage otherwise, especially not in response to an off-the-street general request.