AFAIK, the only truly decentralized cross-chain exchange out there is Thorchain (100M TVL)[1]. The rates/fees are a bit high though, but if you don't mind that, it's probably the best option out there.
[1]
https://thorchain.org/swapWhere can you find such sites?
I've been looking for something like this on google for days with no success
Use any DEX listed on Bestchange or kycnot.me to exchange your altcoins for Bitcoin, but do it in small batches or you will almost certainly lose the whole thing.
How can I rule out that the pages are really safe?
Not sure why you're started to be an Ethereum whale when the token is centralized and AFAIK there's no ERC20 wallet support run over Tor browser, so when you're use less privacy browser, you're not actually anonymous.
As you have mentioned before your choice is using low liquidity exchange (DEX) but the fee is quite friendly if someone willing to trade 1:1 or just choose instant exchange where you will pay high fee.
At dydx you can only trade with ERC20 ( USDC )
I use my own node, unfortunately Tor is not possible with ETH that's true, but I use 2 VPN connected in a row (so I'm already anonymous with ETH)
do you have some examples for DEX and instant exchanges?