I posted a similar request in 2015.
Diagramming App
Things get confusing when CAD and Visio are used in the same sentence.
By definition, CAD (computer-aided design) software is used by architects, engineers, drafters, artists, and others to create precision drawings or technical illustrations. CAD software can be used to create two-dimensional (2-D) drawings or three-dimensional (3-D) models.
Whereas Visio is a drawing and diagramming software that includes a variety of pre-drawn shapes and picture elements that can be dragged and dropped onto a blank page or infinite canvas.
For me, if Affinity were to design a diagramming software similar (or better) to Visio, I would be the first in line to purchase it. In 2015, Affinity were very busy developing iOS and Windows version of Designer and Photo in addition to Publisher (replacement for PagePlus). Now that these are in place, it would be nice to know if something like Affinity Diagram is in the works or being considered.