The energy of uranium is ultimately sourced from gravitational potential energy (of collapsing stellar cores or merging neutron stars), not from nuclear energy. Indeed, the process of converting the iron of a pre-collapse stellar core to uranium is highly endothermic from a nuclear perspective, as iron is the lowest energy state of nuclear matter.

Hmm.... tidal power comes from the Moon gravity interacting with Earth. And the Moon was created as a result of an impact of Earth by a large mass early in Solar System's history. So ultimately it is derived from the potential energy of the cloud of gas that coalesced to create Solar System, and not from any fusion or fission inside Sun or other stars.