Imho meltdown/spectre is a bad example from this point of view: it was dealt with very badly, with lack on information to some players (e.g. openbsd if I recall correctly), and earlier disclosure than agreed (with potentially some patches rushed out the door because they were meant for days later)
IIRC OSes that weren't Windows/OSX/Linux didn't get invited to play in the embargo sandbox either until very late or not at all, so e.g. illumos and the BSDs were either completely in the dark or caught with relatively little time to do anything, especially because people inferred a bunch of the details before the embargo was supposed to expire from various patches and snippets of information leaking.
There was also the issue that gregKH complained about, where the different major Linux distros on the embargo basically got siloed by Intel out of talking to each other, so they ended up building their own solutions. [3]
[1] suggests FBSD got to the NDA sandbox relatively shortly before it went public. [2] says OpenBSD indeed did not.
