Yes, digital signatures can be created using both hot wallets and mobile phones. In fact, many popular Bitcoin wallets allow you to create and sign transactions directly from your mobile device or hot wallet.

However, using a hot wallet or mobile phone to sign transactions does come with some additional security risks. Because these types of wallets are connected to the internet, they are potentially vulnerable to hacking or other types of cyber attacks. Additionally, if you lose your mobile device or your hot wallet is compromised, it could give an attacker access to your private keys and allow them to spend your cryptocurrency.

That's why it's important to always use caution when signing transactions using a hot wallet or mobile device. Be sure to use strong passwords, enable two-factor authentication, and take other steps to secure your wallet and protect your private keys. Additionally, it's a good idea to move the majority of your cryptocurrency holdings into cold storage, which is generally considered to be a more secure way to store your funds over the long-term.