My explanation to my students at the bitcoin workshops is this:
Mempool is like giving your transaction to a kid to get on the bus plus bus fare. One hand holds the money, the other one holds bus fare. He waits at the stop, buses come in every 10 minutes. The bus has limited seating. Those who pay more get to be seated. If the bus fare you offered is less than the others waiting, he waits for the next bus to come in about 10 minutes. If the bus is empty, the driver accepts whatever bus fare you offer and gives the kid a seat. That’s your transaction utxo taking the blockchain bus to the miners to be processed.
I follow this bot that tweets out mempool estimates @CoreFeeHelper
The best project to watch the mempool is of course https://mempool.space/ and you can run your own instance on your own node..