LED drivers

My understanding is that these are constant current devices since the LEDs are primarily current devices.
If a LED fitting has a fixed voltage to power the device it will then typically have its own driver/s to feed the LEDs…

Yes, especially if you have a string of LEDs. It’s more efficient running it with a constant current supply (as opposed to a series drop resistor, especially for a mains powered fitting) and input voltage fluctuations won’t affect the intensity of the LEDs