remote wire for heat pump

Howdy all. I have a customer that quoted changing and hydronic system to a heatpump. The salesman forgot to check the stat wire going outside and it only has 2 wires. So we go to install it and luckily they started outside and when they got ready to hook up the T-stat ware, they noticed it only had two wires. This is in a condo building with unit above and below, so there is no way to run new stat wire. Some point in the past I thought I saw a device that was wireless that had relays for the reversing valve. I think all it needed was 27V from the transformer. I realize I would have to replace the thermostat as well, but that is not a big deal. Has anyone seen something like this?

Thanks for the help

source https://hvac-talk.com/vbb/threads/2238926-remote-wire-for-heat-pump?goto=newpost