If OP wants to be able to check his wallet (watch-only) anywhere without having to connect his Nano S to the PC and unlock it, he can do the method above, then go to Wallet -> Information -> Copy the ypub, then import it to create a new independent watch-only wallet (not linked to the Nano S device).
You ONLY need the hardware device connected to check the wallet IF the wallet file is encrypted:
If you don't use encryption, you can open the watching wallet without the device connected. This isn't really a security concern as such, as no private keys or seeds etc are held in the wallet file. So, it only really has privacy implications, insofar that if your wallet file is somehow compromised/stolen, the thief will have access to your YPUB, addresses and transaction history. They can't spend your coins.