Or you could have gods exist independent of worship.
Great, they are independent of worship. Now what?
The gods aren't acting directly on the world, they act through their followers. Nerull has the least number of followers so he has the least impact on the world. Meanwhile Pelor has a massive number of followers and a massive impact on the world. And again, they are supposed to be equals.
In fact, if you make Nerull seperate from worship, would he even have any churches? How could he get clerics. It would all be cults and hidden sects.
Which tying this back into a different thread, really just makes him a Demon Lord equivalent.
Also, your description of Nerull sounds a lot like the religion from the movie Beneath the Planet of the Apes (and from the song Everlasting Bomb by the band Widescreen Mode)
Never been exposed to either of those things
I see where you're going with this, but if the sun is a step above/outside all these assorted pantheistic deities, doesn't that make them more appealing as an object of worship, at least to a certain mindset?
Sure, but that is where Druid's come in.
The way I divided Clerics and Druids is how their power is created. Clerics are a community, all of the energy of the worship of a specific deity is channeled into that deity, then who then divides it amongst the clerics or other works. If the commnunity it destroyed, the god is killed or at least severely weakened.
Druids draw their power from ancient spirits, the forces of nature that might have existed before people and the gods. A druid gathering excess energy from the Sun Spirit would find that that energy never really goes away, unless the sun itself was destroyed. To de-power druids, you have to destroy the world, but the world would continue to exist even if all the druids were killed.
So, the sun can be worshiped, but it doesn't interact with that worship in any way. It is just existing as it has always existed. Deities want to interact with their worshipers.