As of 2022/7/6, Sepolia has switched to PoS. The window to do some mining has closed.
It's mid 2022, Ethereum is still PoW and motoring towards merge / PoS. Surviving testnets will be Sepolia - currently PoW - and Goerli. Ropsten will be merged and then deprecated, Rinkeby and Kovan won't be merged.
I want to "get ready" for some Sepolia testing pre- and post-merge. Sepolia will not have a public validator set; testing post-merge will be limited to running applications on it. As Sepolia is PoW, I can actually go mine myself some SepplETH. Here's how.