yeah, exactly. there's a company called MrCool that does something similar (https://mrcool.com/diy-4th-generation/), but the head (the indoor part that provides the heat/cooling) is designed to be mounted.

if this were popular you'd see old houses retrofitted with pluggable holes where you could feed the lineset through and seal as necessary for temporary heat/cooling, or perhaps even permanent.

the installation would be substantially easier if these were like 6000BTU instead of minimum 12000BTU per head, so it could be run on say, ~8 amps and be plugged inside.

Coolant supply and return, both fully insulated. And condensate drain line, and power wires, and control wires. Do-able, but more complex than one might initially think.