As they said --air-gapped smartphones are much safer than the air-gapped PC which are vulnerable to hacking, did you know that even fully air-gapped PC can exfiltrate information through the output radio signals generated by the computer or call [electromagnetism].
Also expert says that through [ultrasonic waves] a virus can be used to steal the private key out of the computer.
I had always preferred the hardware wallet over the old PC or phone for cold storage, they don't have the security features that hardware wallets have. A hardware wallet has minimal attack surfaces not unless they steal it from you personally.
So no way for the old phone to be a cold storage wallet or worst a PC to be a cold storage wallet, however --I am overthinking for 25% way of a possible scam using an air-gapped wallet.
At the end of the day an air-gap PC is the safest option compared to both phones and hardware wallets because it is
physically disconnected from the rest of the world whereas hardware wallets are not and phones are extremely hard to made truly air-gap.
The attacks you describe on PC are very complicated and more theoretical than practical specially since the attacker needs to be close to the PC and in some of these attacks they need
physical access. Meanwhile there are other attack vectors on hardware wallets that are being connected to a system that could be infected. Granted they too are theoretical but there has been real cases in the past and when comparing it with your examples they are more serious.