Can I, as a miner somehow force a block to be confirmed with a desired blockhash?

Lets say Im a miner, and I want block number 1000 to produce a specific blockhash, because that will yield me a reward. The blockhash last 5 digits must be 76865. And this MUST happen on block 1000. (random numbers)

Is the blockhash actually random until confirmed?

Is this even possible for a miner?

If yes, what does it take?

What does it take attempting this kind of attack on Ethereum vs a sidechain like Polygon where gas is cheaper?

Thanks.