Modular endograft devices and associated systems and methods are disclosed herein. In several embodiments, an endograft system can include constrained first and second endograft devices that extend across a vascular defect and expanded to press mating septal walls against each other. At least one of the endograft devices can include a fenestration that is aligned with a renal artery to provide bloodflow to the artery. A delivery device configured in accordance with the present technology can include a guidewire that passes through the fenestration to guide the endograft to an implant site and self align the fenestration with the renal artery to facilitate connection of the endograft to the renal artery. An additional stent can be connected to the fenestration to secure the renal artery to the endograft device.
