In general, candidates who are on the end of a rescinded offer do not have much in terms of legal recourse. Although it varies from state to state, unless otherwise specified, employment is “at-will”, meaning either the employer or the employee can terminate the employment relationship at any time and for any reason. Consequently, candidates have a difficult time enforcing a job offer or recovering damages for a rescinded offer when there is no duty on the part of the employer to keep the individual employed.

That said, there are some circumstances in which a candidate may have legal recourse if an employer rescinds a job offer. The candidate may be able to pursue a claim against the employer under one of the following theories: 1) Promissory estoppel, 2) Fraudulent misrepresentation, 3) Breach of contract, and 4) Discrimination.

https://career.mst.edu/resources/students/job-offers-and-rejections/

Promissory estoppel cases are generally a case of the juice not being worth the squeeze, but based on the information in the OP (i.e. hefty demonstrable sunk costs) this particular circumstance is likely to be an exception.