I can not love this development project enough its the peak of Android custom ROM. I am curious though as to what they have changed so much that it is going to be more difficult.

Sounds like there are lots of causes: the project losing a senior dev who got conscripted to fight in a war. Not getting access to an OEM rom early on. Google changing a lot of the code around lock screen and other features (which makes porting over their custom changes on top of it take more time).

Oh, they also had the issue that one of the leading devs got forcibly conscripted.

Quickly scanning GrapheneOS's posts I couldn't find any detail about the technical challenges. They'll probably post about it in the coming months

I mean, conscription is per definition forced, isn't it?

Is such nitpicking necessary? It derails the conversation

Yes and no. In some countries and depending on peace or war times, you are forced into service, but you can choose to do military service or be a conscientious objector and work as a hospital aide.

Yes, but the connotation here was "conscripted which is a bad thing that made them unhappy."

Okay, but what are the changes that made porting more difficult?

Not publishing Pixel-specific code, moving some of the features from AOSP to Google services.

GrapheneOS currently only runs on Pixels because they're only one Android phones with a reasonable security architecture.