I am playing a cleric of wee jas currently. Think we are about to hit 9th!
For many reasons I simply prefer the Greyhawk deities to many others. Their domains and mystique are where it’s at. I think Bane and…helm? Are interesting for FR but that is mostly it.
As to how are they used…in my campaign all gods can be worshipped but they all have small dying cults. The real action is with the archon a that follow the overgrown. Most deities are like saints and are not major players comparatively. So when it’s my turn to DM, you can bring what you want and reject the campaign deities.
That said, I even take Greyhawk deities into my pal’s very loose FR campaign. I don’t have to push too hard. Their cult is not a major player in the world and I accept that: but as I grow in power maybe their influence will grow as well!
Bottom line is I just never gelled with the FR pantheon post 1st edition.
I am not 100% sure as to why. I have a nice 3rd edition book about the gods (can’t think of the name) and the whisky weird art for many FR gods along with their general description left a bad taste.
Just not for me. Lathander, mystrs etc…looking at you