Is atomic swaps available for someone reasonably techical right now? I keep my coins in a trezor and ledger. For the upcoming hard-fork, I would like to keep the coins with private keys.

However, I think there is a big risk in the upcoming bitcoin fork that is not priced in. Therefore I plan to sell my bitcoins for ethereum maybe 24h before the fork. Are there any tools and/or markets for doing this right now with atomic swaps or is it more like a technical prototype?
Atomic swaps can be performed, yes, they aren't just a theoretical thing. For example here is a tool on GitHub for creating atomic swap transactions between Decred, Bitcoin Core, Litecoin and a couple of other coins: https://github.com/decred/atomicswap

But I do not know of any exchanges or markets which support doing atomic swaps, you would probably have to manually find someone who is willing to sell ETH for BTC and do an atomic swap with you at an agreed price. LocalBitcoins might be a starting place to look, I'm unsure.

Hope that helps though