Sepolia is now on PoS
As of 2022/7/6, Sepolia has switched to PoS. The window to do some mining has closed.
Testnets after merge (original, old content from here)
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.