If the publisher of a game does not offer the game to GOG to sell here, there is no missed chance because there never was a chance. The only way games come here is if the game publisher of a game and GOG enter into negotiations to release a game here and successfully establish mutually beneficial terms.

Now if GOG is offered such a game and refuses it for some reason or drags their feet and nothing comes of it, then that would definitely be a missed opportunity, but for an opportunity to be missed there first has to be an opportunity.

In reality though GOG is always on top of these things and going way out of their way to communicate with publishers to convince them to release games here, so if there is at all in any way possible a remote opportunity for them to get such a game here, we can all bet our boots that they're already on top of it a long time ago and if they're successful at it then we will see it here. If not, then most likely the opportunity never presented itself, or mutually acceptable terms couldn't be reached.

We'll almost never know the truth though as such conversations are private business dealings.