Paper wallets are used for gifts and for storage when you want to move to a country or other item
Personal, I think gifting paper wallets is bad idea. The recipient of the paper wallet has to trust completely that the sender has created and printed the paper wallet in a secure fashion, and also has to trust completely that the sender isn't keeping a copy of the private keys for themselves. Any time I have wanted to gift bitcoin I've just made a normal transaction, and the one time I received a paper wallet as a gift I swept the funds immediately to my own wallet. If you are giving a gift of bitcoin to someone who is new to bitcoin and does not have their own wallet yet, then all the more reason not to use a paper wallet and instead teach them how to securely and safely store their own funds without relying on third parties.
but they are not suitable as a way to store all of your savings.
Why not? If we are talking about savings, i.e. money that you are holding long term as opposed to money you are spending day-to-day, then paper wallets are one of the best ways to store your savings.
You can buy a phone at a much cheaper price than device wallets and convert it to a solid device.
Even a phone in airplane mode can still receive radio frequency data, and can still connected to WiFi, Bluetooth, or other connectivity methods. If you want to create your own airgapped device, better to use an old laptop with the WiFi (+/- Bluetooth) hardware physically removed.