I would rather download Ian Coleman mnemonic on github https://github.com/iancoleman/bip39

I use tail OS with no internet connection to generate my address.

Ian Coleman mnemonic is applying the same protocol to generate 24 words phrases and the resulting addresses as any other code. So what is the issue?

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

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.

thanks