Ask HN: Does anyone have experience with PEOs-Professional Employer Organization

We have a known resource that we want to hire but is not willing to relocate to US. Therefore we want to hire internationally a fully remote employee. A PEO sounds like an exact fit to our need. But we don't fully understand all of the implications. What are the legal risks, liabilities, and concerns that we need to mitigate? What should we consider when evaluating companies? Is this really a viable option? How is this different that hiring a contrator through another company? Should we even consider this?