Declared pledge or actual pledge

Which value is used for rewards, declared pledge or actual pledge?

For example: I declare 1 Ada pledge, but my pledge wallet has 10 million Ada in it. Does my pool receive the same rewards as if I declared 10 million pledge?

Yes, you have pledged 1 ADA right?

Doesn’t matter because the pool will receive the pool rewards (pool cost + margin + %tx fees) first and then the rest of the rewards are shared % to the stake amount

I think you’ve misunderstood. Pools with high pledge are awarded more ADA per block than pools without pledge.

My question is that when rewards are calculated, is the pool rewarded based on actual pledge in the wallet or the amount declared.

Totally wrong

Check the big pools with 100/1000 ADA pledged

I understand your question. Basically you want to know if you can partially pledge an amount in your wallet, say 1000 out of a 2000 total balance. My understanding is that the whole amount of your wallet will count as your pledge even if you only declared a 1000 ADA pledge on chain. Hope that helps.

According to the documentation and the rewards calculator, the pledge should have effect on the total rewards:
https://docs.cardano.org/core-concepts/pledging-rewards
https://cardano.org/calculator/?calculator=operator

First I thought the pledge amount a0 from the formula is the one that is declared in the pool certificate, as that is the info delegators will look up…

…but looking at the delegator rewards calculator there is no pledge setting but only a stake pool operator's stake which makes me believe now that the a0 parameter is the pledge wallet ADA amount (10 million in your case). Probably that’s why big pools have pledge 100 as Alex mentioned.
https://cardano.org/calculator/?calculator=delegator