You shouldn't trust any custodial service with your bitcoin. Any custodial services is able to freeze your fund at any time for any reason. There's also the possibility that they get hacked or they are closed at any time. When you use a custodial service, you don't actually own any bitcoin.
You should always use non-custodial wallets, so you can have full control over your fund.
Not your keys, not your coins.But enough about that topic, is there any sound way to earn with your Bitcoins while I stay true to the principle ideal of? My keys, my Bitcoins with at least having some anonymity.
No.
You can't have full control over your fund and get interest at the same time.