Just looked and it seems that Bitbox is also open source and have secure element chip like Jade. Coldcard and Trezor are not open source. Of course, open source does not automatically mean it's safe and cannot contain backdoors but at least everyone can verify, view, build and flash the firmware and bootloader.
Discussion
This is a long running argument.
Coinkite makes hardware not just software, so the cost base is different. The restriction in their license is don't make exact copy and sell it as your own. The code is open source and often scrutinized.