TNO = trans neptunian object, basically far out dwarf planet
Obviously there would be less sun to greenhouse, but theoretically could that be a way to have closer-to-earth habitats far away from a star?
the greenhouse effect multiplies existing heat, it doesn’t create it - and at pluto’s distance, solar energy is ~1/1600th of earth’s, so even perfect heat trapping would still leave you with a freezing world (you’d need internal heat sources like geothermal or artifical heating to make it habitable)
Methane is a powerful greenhouse gas, and it’s the main character of Titan’s atmosphere, and still, Titan is extremely cold. (And Titan is closer to the sun then TNOs)
So I’m inclined to say that greenhouse-effect alone would not be enough to keep TNOs warm like Earth.
Additionally, Pluto has neither a strong gravity nor a magnetic field, nor tidal gravity from a parent planet.
It wouldn’t be able to retain the atmosphere for long.
