No he doesn't need to buy another Trezor device, Trezor uses standard BIP39 seeds and standard derivation paths for Bitcoin : BIP44(legacy), BIP48(multisig), BIP49(p2sh segwit) and BIP84(native segwit). Then he can import his seed in any standard wallet if he loses his device.
https://wiki.trezor.io/Standard_derivation_pathsOk. Now I get it. I've been using online wallets since 2017 and never had any issue but I think it's better to be wise and get smarter. So with the standard BIP39 I can import my seed from anywhere?
Thanks guys
Yes you can import it in any wallet accepting BIP39 seeds, that is to say in any standard wallet. They usually use standard derivation paths too, but the one you want to try doesn't use it, you just need to find another using BIP44 derivation path.