I have one Ledger device, I want to input the private key not the phrase, is there a way to store the private key in the Ledger? I prefer to have a specific public address rather than a random one by phrase.
No you can't do that with hardware wallets, but you can generate seed phrase offline and import it in your ledger wallet, that way you don't have to trust device generating anything.
Note that private keys or seed phrases should never be generated online, and you can just send coins from your old address to new one.
I don't get it for leak things, does vanity is not safe? there is more than safe with phrase ?
Can you translate this in english language?
Both seed phrase and private keys can be safe or unsafe, depending only on you and if you are doing things correctly or not,
I am not know many about security or such program. how to proved the hardware is safe? 'cause I bought them from 3rd party.
You can verify if your device is genuine by following instructions on ledger website, but it should be fine if device was new and unopened.
It's better to buy from official store or resellers, but you can always reset device and check inside for potential malicious changes.
https://support.ledger.com/hc/en-us/articles/4404389367057-Is-my-Ledger-device-genuine-?docs=true