I would go with the bulbs
The fixtures are nice but they can have high failure rates and are more difficult to replace, as you have to replace the whole unit.
Bulbs on the other hand are easy to replace if they fail, they’re standardized so anyone can walk to the store and pick up an A19 60W equivalent.
Surely that can’t be uniform random though
But they’re just using it for a seed, so the output would be impossible to predict, but it feels like a checksum or something would approach a Gaussian distribution (the more numbers you add up, the more Gaussian it would be, since we know an image will have a mean and finite variance).