Maybe it'd be useful the other way around: as a DM, let an AI play the PCs to test out your campaigns and dungeons. I wonder how good it would be at finding the weak/missing points that players do, and whether it would give you an idea whether the challenges are too hard or easy.
This is one of the good potential use cases for current gen AI; simulating a scenario again and again and seeing what effect various changes will have on the average outcome... Probably needs an API for having LLMs play with online table top simulating websites or so, I have no idea about any of the sites for online TTRPGs though and their terms of use...