There is a recent push for GPT-derived "apps" (rumor has it that this is the
basis for the OpenAI / Sam Altman circus).
This video shows how these can be created from sources like PDFs to be customized with particular areas of expertise.
https://www.youtube.com/watch?v=QjtboPHrsJI&ab_channel=TWiTTechPodcastNetwork
This would clearly be useful to developing classroom use or developing expertise in a particular companies "mission" or gathering research papers in a particular area or ... you get the idea. Fill it with your favorite textbooks and poof ... an assistant.
The ease with which these can be developed offers vast possibilities.