Unfortunately none of those options will work with single output LED bars, specially the ones with a wide input voltage.
Those lights will have either an external driver or an internal "buck" converter to provide the correct voltage needed by the LED array regardless of input voltage variation.
If You were to wire your own LED array you could use a PWM driver to vary the intensity.
That idea would work with halogen type bulbs.
Edit:
Of course You can buy the ones specifically designed for Hi/Lo operation:
https://www.auxbeam.com/77719526