It may have been done so little that anything is progress, BUT you are ignoring the fact that the NWN and NWN2 DM modes were really really good so they are very valuable examples of what you might want to achieve.

Also, the gentleman up earlier in the comments talking about NWN2's persistent worlds is ignoring something, NWN2's big persistent worlds existed INSPITE of the tool set in the game. The tool set wasn't made for such a thing and was eventually modded to all hell till it supported the big 50+ player persistent worlds. It's actually a marvel to be honest, a true testament to the will of a modding community and I believe that with the same amount of love DivOS2 could feasibly do the same even if Larian doesn't implement it themselves, as long as the base DM mode is powerful enough to spark the desire and frankly something shit like Sword Coast Legends won't spark the desire.