Jade hardware wallet is already in this list for some time and I know it's open source.

New hardware wallet is added today called Hito.
They are still in pre-sale phase, and they promised to release open source code when they complete pre-sale, but I would be careful and wait for github links to be released.
Additionally, someone (like WalletScrutiny) should verify if code is going to be reproducible or not inreality.