Quote from: fred21 on Today at 10:16:00 AM

So what is the issue?

The issue is it uses Javascript.

Did you read the post hosseinimr93 linked to above? The bottom line is using Javascript is insecure and does not guarantee your safety. If you are going to all the hassle of using a live OS to set up genuine cold storage, then why would you want to use insecure code to generate your seed phrase?

Quote from: fred21 on Today at 10:16:00 AM

Also what would you recommend to generate BTC private Keys for cold storage? I don't trust hardware wallet.

Use good quality, reputable, open source wallet software such as Core, Electrum, or Sparrow. Review the code yourself if you have the ability to do so. Verify all downloads (this includes your downloads of Tails).

Quote from: fred21 on Today at 10:16:00 AM

About Electrum : Do you know if I can use it in tail OS and if it can be used like Ian Coleman to generate keys and mnemonic phrase only.

Yes. Tails has Electrum already installed, so this is very easy to do.