I am fully aware of
this post discussing how Yubikeys that have serial numbers larger than 3000000 (with some exceptions) are "no longer configured with fixed card manager keys". The obvious implication is that these devices are not going to be suitable for development purposes.
However, it isn't entirely clear to me if this excludes official yubico software updates. Can Yubico provide signed software updates that can add or update new apps on the card, or is this not possible?
Does yubico just set the card manager key to a random value, or does yubico have a way to calculate the card manager keys (maybe from an HMAC of the serial number with some secret value)?
-- Robert