If I consider buying a security token similar to a Yubikey, I'll try hard to buy one with open firmware, and preferably open enough hardware. Something that has

If I consider buying a security token similar to a Yubikey, I'll try hard to buy one with open firmware, and preferably open enough hardware. Something that has been independently inspected, and something that allows me to load the firmware I control and can inspect. (The ability to only load it once would be fine; an ability to securely update it would be really nice.)