Morphing structures that can adapt their mechanical properties to changing flight conditions are a viable actuator solution for multifunctional wingtip devices. Compliant morphing structures offer distinctive advantages, including high power density, continuous and distributed actuation, and reduced system complexity. However, they face the contradictory requirement of undergoing significant deformation while resisting high external loads. This contradiction can be managed with actuators that adapt their structural stiffness by changing the fluid pressure in structure-integrated chambers. This chapter presents a detailed literature review on morphing structures with structure-integrated fluidic actuation to assess whether such structures represent a viable actuation technology for critical aircraft structures. Within the research landscape of compliant fluidic actuators, pressure-actuated cellular structures (PACS) are a promising actuator technology inspired by the nastic movement of plants. The biomimetic concept of PACS consists of multiple rows of pressurized polygonal cells composed of rigid walls and flexure hinges. By controlling the cell pressurization, PACS bend upwards or downwards and simultaneously adjust their structural stiffness. This chapter outlines previous accomplishments and the design framework of PACS, and highlights the potential of PACS actuators for application as multifunctional wingtip devices.