In here youre taking about miners which are a part of a mining pool?
If you are running your mining equipment as part of a pool, then generally speaking the pool will run multiple nodes each with their own mempool, use that information to build candidate blocks, and then send those candidate blocks to the miners to be worked out. Each individual miner doesn't need to run their own node, although many will. If you are mining solo, then you must run a node in order to receive broadcasted transactions to your mempool and then attempt to include them in a block you are attempting to mine.
Mining hardware does not have a mempool. It is nodes which have a mempool, and then use that information to create blocks for the mining equipment to work on.
But what about a node who launched his own Bitcoin Core client? Does he have a mempool? Cause as far as I know yes, he does.
Yes. Bitcoin Core is a full node, and as with any full node, will have a mempool.