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 permanently

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.