Metamask released ETH to fiat (cash) withdrawals in few countries (USA, parts of Europe), but at this point service just takes too large fees (around 9%) to make up for convenience, and it should not be recommended at this stage.

So as many of you have heard yesterday Metamask released a new feature that provides service to turn your ETH on your metamask wallet directly (or not so directly) to your bank account or even Paypal. They partnered with few of the providers like Moonpay, Transak and Banxa.

The way to sell it is to go to Metamask portfolio site, connect your wallet and click on 'Sell' option. Then you input the amount you want to sell (0.01 ETH is minimum) and on the right side you will get quotes on how much you could get from what exact provider, and choose the option that fits you the most (I got 2 quotes when trying: from Moonpay and Transak - Moonpay's one looked a little better considering I would get slightly larger fiat amount with it).

The thing is you have to be KYC-ed on the provider you're trying to sell that ETH to. So if you're going through Moonpay option you have to be KYC-ed there, so you might as well just do all of that directly on Moonpay's website. Anyways once the transaction on-chain is being processed, you have to confirm and pay the current gas fees, you pay more considering the hidden ask/bid spread fees that Moonpay has, and on top of that Metamask takes 1% fee on top of it.

One Twitter user from UK did the transaction and overall he gave 65.1 GBP worth of ETH (0.05 ETH) at the moment and received on his bank account 59.42 GBP in fiat, meaning they paid the fees of around 9% which is definitely not a small amount. You'd be much better selling your ETH, especially larger sums on regular CEXes. This user also stated that transfer to his bank account took just 5 minutes.