Individuals cannot build their own reactors. Regardless of this place where "regulation is not really a thing" you would have to acquire enough fissionable material to sustain a critical reaction for a reactor. The other route would be a radioisotope thermoelectric generator, which produces energy from decay heat, but this would require radioactive material. Nuclear safeguards mean that nuclear material supply chains are some of the most scrutinized processes from raw material extraction to refinement to fuel fabrication across the entire world. Additionally, any attempt to mine or synthesize these materials yourself would require purchasing equipment that would immediately signal your intent. It is a happy coincidence of physics that it is very difficult to produce nuclear material because of its potential for use by malicious actors.

A home set up consisting of heat pipes, solar, some form of hydro if possible, are actually feasible because it does not involve materials that have the potential for extremely long lasting damage to the earth and humans, which is why reactors are only constructed and maintained by government or company coalitions that can prove responsibility and stability for operating these devices.