Your private keys never get touched, written, displayed, put on RAM/disk, etc with a hardware device.
Except, you are trusting these startup companies did not do any tampering with their hardware like a backdoor for instance. If I was building a company like that, I would be very very very tempted to "accidentally" leave a small debugging backdoor for someday in future.
Personally this is what I do, which I consider to be the most secure way to save your crypto. I wrote a small script on my macbook from early 2000s that I dont use for anything else. This script generated the addresses and the corresponding BIP passphrase, and displayed the address on screen. I transferred the crypto I am hodling to these addresses. This wallet exists only on a couple pieces of paper as BIP phrase and nowhere else. Far far more secure than a hardware wallet which you dont know what is really inside it.
Except, you are trusting these startup companies did not do any tampering with their hardware like a backdoor for instance. If I was building a company like that, I would be very very very tempted to "accidentally" leave a small debugging backdoor for someday in future.
Personally this is what I do, which I consider to be the most secure way to save your crypto. I wrote a small script on my macbook from early 2000s that I dont use for anything else. This script generated the addresses and the corresponding BIP passphrase, and displayed the address on screen. I transferred the crypto I am hodling to these addresses. This wallet exists only on a couple pieces of paper as BIP phrase and nowhere else. Far far more secure than a hardware wallet which you dont know what is really inside it.