I think I may well end up with a Nano X to be honest, seems to have a LOT more storage on it, and it can be used directly with a phone.
The Ledger Nano S can connect to a smartphone too. Of course, using a cable because the Nano S does not have Bluetooth features like the Nano X.
Just to go on from this, can I then sell my Nano S, or does the recovery phrase stay the same so it means it's now vulnerable to a buyer? I know they aren't expensive, but a mate may well be getting into crypto so could be of use to him?
You can sell the unused Nano S by resetting it to factory settings first.
Resetting the device to factory settings removes all private keys, applications, and settings from your Ledger Nano S device.
Nano S and Nano X can share the same seed to have the same wallet and make transactions on either of the two devices. By the way, why isn't the Nano S just used as hardware wallet to backup the Nano X that you are going to buy?