In the context of new power system development, releasing the flexible regulation potential of distributed resources is crucial for promoting renewable energy consumption and improving the safe, economical, and low-carbon operation of power systems. Distributed resource aggregation is an important organizational form for enabling numerous dispersed resources to participate in supply-demand interactions of new power systems. Clarifying the intrinsic relationship and coordinated development pathways between the two is significant for enhancing the supply-demand interaction and flexibility capabilities of new power systems. This study summarizes the implications of new supply-demand interactions from the perspectives of interactive entities, aggregation methods, and market mechanisms. It also clarifies the stage characteristics of planned, market-based, and autonomous supply-demand interactions, and reviews international research progress on new supply-demand interactions. Moreover, the study analyzes the characteristics of new supply-demand interactions from three dimensions: interaction elements, interaction behaviors, and interaction technologies. It further analyzes the role of distributed resource aggregation, and summarizes major challenges it faces in perception, modeling, regulation, planning, and trading links from information, physical, and social perspectives. Furthermore, the study reviews the prospective applications of distributed resource aggregation from four aspects: typical scenarios, key technologies, flexible mechanisms, and development prospect. Specifically, the typical scenarios involve vehicle-grid, electricity-hydrogen, and electricity-carbon interactions. The key technologies include diverse small-scale sensing, game-theoretic modeling of interactive behavior, data-driven intelligent decision-making, bidirectional dynamic aggregation for heterogeneous resources, and multi-market quantitative trading. By leveraging the flexible mechanisms of value co-creation through individual alliances and blockchain-based trusted multi-party transaction, the prospects for optimizing resource allocation across society and promoting the inclusive and secure development of energy systems are expected to be realized. These insights can provide references for theoretical studies, mechanism design, and engineering applications of power system supply-demand interactions, thereby supporting the improvement of flexibility in new power systems.