Can I use my 24 word mnemonic backup seed phrase that created on my Ledger Nano S on other devices that use a 24 word seed phrase? An example would be the Trezor hardware wallet.
You can use them, but you need to ensure that the hardware wallets use the same address derivation paths. For the hardware wallets you mentioned (Trezor and Ledger) both of them use the BIP 39/BIP 44 derivation paths, so that should work, especially in the case of Bitcoin. However care has to be taken for certain coins (ETH or any other ERC-20 for example) where these wallets do not use the same derivation paths.