The fact that they can be moved shows that they will be moved.
No, it doesn't. If you throw away your seed phrase and delete your wallet, your balance will remain the same, but the coins will never be moved again. You can't consider those into circulation.
Bitcoin supply is 21 million and not more than that but also not less than that.
What about the probably burnt coins (OP_RETURN) or the unclaimed reward from some miners? It won't be 21 million, neither 20,999,999.9769.