Ledger Live seems to be using Moonpay[1] so I would imagine that they might be charging users a bit more.
As for your second question, then any decent exchange should allow you to withdraw your funds to your ledger or any other wallet. And from what I understood from your last post, that should also include Revolut. Now whether they charge more or fewer fees than other exchanges, I'm not sure.
In addition to Kraken, you should also look into Coinbase.
[1]
https://www.ledger.com/academy/series/ledger-how-tos/how-to-buy-crypto-through-ledger-liveI appreciate all your effort to help me and clarify me question that keep bugging my head.
About fees , there are fees to buy BTC or Ether , sell them for Eur/USd and even transfer them to a wallet right ?