I've read that Trezor had some flaws/vulnerabilities regarding the mechanism used to secure the seed (using a passphrase). Not sure if that's been addressed already, though. I'd try out the Passport wallet with the Monero-supported firmware. The device looks nice, although it has a hefty price tag. If there was any cheaper alternatives, it would've been better.
Good to know. If Trezor is a rock-solid choice in terms of security/reliality, what could go wrong? Not sure if I'll get this one or the Passport.
How about installing an open source monero wallet on an old device that is air gapped (completely not connected to the internet)?
Probably running Linux OS.
Not that's an open source hardware wallet created by you and it's cheap
Thanks for your suggestion. But I'm more into mobile devices than PCs. Particularly Android. An open source hardware wallet + Android would be the ideal setup for me. I will keep this in mind if I want to put my XMR in cold storage, though.