How much other yield does it give you? Lets say you have 7 cities. Lets say you have Quarry-based monopoly, Marble and couple of Stones
+2

/+1

/+1

per city and +1

per Quarry. That is +14

/+7

/+7

and +10

on Resources
For God of Open Sky you are guaranteed to have more Pastures than Quarries, lets say you have 3-4 pastures per city, which is possible for sure. You get +73

(3.5*3*7) AND no less than +20

. In addition you actually have chances to found religion. With Craftsmen you don't have it unless you are Ethiopia or Aztec.
If this is the logic we use, I propose a change to earth mother. Because if you have more pastures than mines, its weaker than open sky.
I propose a change to God of the Sea. Because if you have more pastures than fishing boats, its weaker than open sky.
I propose a change to goddess of the hunt. Because if you have more pastures than camps, its weaker than open sky.
I have to challenge numbers here. I don't get 7 cities settled all that quickly. In city #7 I certainly won't be have 4 pastures connected before the religion race is over.
I don't see how a quarry monopoly with stone and marble only reaches 10 quarries. Playing on tiny maybe? On standard a monopoly is usually 8 copies, add "a couple of stones" and the marble and you should be at 13 or 14.
I have to challenge the founding claim. I have founded using quarry faith and England, Songhai, and India. Its very good on jade.
Is it too niche? I take it more often than other pantheons, such as stars and sky, open sky, expanse, love, and renewal. Yes, you have to research construction and I know you don't want to. If you don't want to, pick a different pantheon.
If you want to change it, I'd suggest making salt a quarry. Salt is buffed by the stoneworks which leads to a very high production opening with this option (basically how you play it with Jade currently). Then the pantheon has synergy with two monopolies rather than just one. You could make amber or lapiz lazuli a mine in compensation.
Edit: Or remove the +2 gold on monuments and give the quarries/stoneworks +1 gold.