IIUC it's only half from the Sun's gravity well, the other half of that energy gradient is from the Moon's gravity well.

Also IIUC "energy from the sun" is really shorthand for "Energy emitted by solar fusion", which tidal would not involve.

The laws of gravity are entirely symmetric, so it doesn't seem fair to attribute it specifically to the sun; also, the energy in this case is coming out of the "v" in earth's good old 0.5mv^2 kinetic energy relative to the sun.

Good pedantry, but then we can argue that the origin of fossil fuels is geothermal (if we ascribe the origin of life to hydrothermal vents).