If I ever lose my Ledger Nano S or It simply stop working for one reason or another, is the only way to recover my coins is by buying another one and enter the passphrase again? I want to know If there is some kind of software (open source) where I could just it to recover my coins without the need of buying another Ledger wallet
Well, there are options...
https://iancoleman.github.io/bip39/ and
http://bip32.org/ should work, altough you do need the correct derivation paths.
If you know some python, you can actually write a script to do everything yourself.
An other option would be to use a BIP39/BIP44 compatible wallet and restore it with your written down seed words.
This being said, with the price of a nano s, i'd personally just buy a new one, and use the mnemonic to restore my wallets instead of messing around with other tools...